Revised Functional Capacity Index as a predictor of outcome following injury

BACKGROUND

Assessment of functional outcomes in survivors of severe injury is an identified priority for trauma systems. The predictive Functional Capacity Index (pFCI) within the 2008 Abbreviated Injury Scale dictionary (pFCI08) offers a widely available tool for predicting functional outcomes without requiring long-term follow-up. This study aimed to assess the 12-month functional outcome predictions of pFCI08 in a major trauma population, and to test the assumptions made by its developers to ensure population homogeneity.

METHODS

Patients with major trauma from Victoria, Australia, were followed up using routine telephone interviews. Assessment of survivors 12 months after injury included the Glasgow Outcome Scale - Extended (GOS-E). κ scores were used to measure agreement between pFCI08 and assessed GOS-E scores.

RESULTS

Of 20 098 patients with severe injury, 12 417 had both pFCI08 and GOS-E scoring available at 12 months. The quadratic weighted κ score across this population was 0·170; this increased to 0·244 in the subgroup of 1939 patients who met all pFCI assumptions. However, expanding the age range used in this group did not significantly affect κ scores until patients over the age of 70 years were included.

DISCUSSION

The pFCI08 has only a slight agreement with outcomes following major trauma. However, the age limits in the pFCI development assumptions are unnecessarily restrictive. The pFCI08 may be able to contribute to future systems predicting functional outcomes following severe injury, but is likely to explain only a small proportion of the variability in patient outcomes.

Occupant-to-occupant contact injury in motor vehicle crashes

OBJECTIVE

This is a descriptive study of the frequency and risk of occupant-to-occupant contact injury by crash type and occupant age. It focused on rear impacts because of a recent Senate inquiry.

METHODS

1994-2013 NASS-CDS data were used to investigate the effects of occupant-to-occupant contact on the risk of serious-to-fatal injury (Abbreviated Injury Scale [AIS] 3+) by crash type and age group. NASS-CDS in-depth cases were analyzed to identify crash circumstances for AIS 3+ occupant-to-occupant contact injury in rear crashes.

RESULTS

Serious injury (AIS 3+) due to occupant-to-occupant contact was uncommon. It represented only 0.84% of all AIS 3+ injury for all age groups. The overall risk of AIS 3+ occupant-to-occupant contact injury was 0.042 ± 0.007%. The highest incidence was in side impacts (69.8%) followed by rollovers (22.9%). Occupant-to-occupant contact injury risk was lower in rear impacts than in other crash types, at 0.0078 ± 0.0054%. The highest risk of AIS 3+ injury with occupant-to-occupant was for the <9-year-old age group when compared to other age groups for all crash types. The risk was 0.051 ± 0.026%, representing 2.69% of all AIS 3+ injury in the <9-year-old age group. Only 4.2% of AIS 3+ occupant-to-occupant contact injury occurred to children <9 years old in rear impacts. The corresponding injury risk was lowest in rear impacts, at 0.014 ± 0.014%%, when compared to other crash types. The analysis of in-depth NASS-CDS cases of occupant-to-occupant contact injury in children< 9 years old involved in rear impacts identified very severe collisions in older model vehicles with deformation of the occupant compartment and yielding front seats as main factors for the contact injury. Front seat occupants injuring rear-seated children was not identified in the in-depth NASS-CDS cases.

CONCLUSIONS

AIS 3+ occupant-to-occupant contact injury occurs primarily in side impacts and rollovers. Most contact injury is to adults (89.4% incidence). Occupant-to-occupant contact injury to children is rare in rear impacts.

Brainstem injury in motor vehicle crashes

OBJECTIVE

This is a descriptive study of the frequency and risk for brainstem injury by crash type, belt use, and crash severity (delta-V). NASS-CDS electronic cases were reviewed to see whether the transition from vehicles without advanced airbags and seat belts and side airbags and curtains to vehicles with the safety technologies has influenced the risk for brainstem injury.

METHODS

1994-2013 NASS-CDS was analyzed to determine the number of brainstem injuries in nonejected adults (15+ years old) in vehicle crashes. Crashes were grouped by front, side, rear, and rollover. The effect of belt use was investigated. Light vehicles were included with model year (MY) 1994+. Occupants with severe head injury (Abbreviated Injury Scale [AIS] 4+) and Maximum Abbreviated Injury Scale (MAIS) 4+F injury were also determined. The risk for injury with standard errors was determined using the MAIS 0+F exposure by belt use and crash type. NASS-CDS electronic cases were studied with brainstem injury in 2001-2013 MY vehicles.

RESULTS

NASS-CDS indicates there are 872 ± 133 cases of brainstem injury per year. About 16.0% of AIS 4+ head injury involves the brainstem. For belted occupants, the highest risk for brainstem injury was in side impacts at 0.065 ± 0.010%. In contrast, the highest risk for brainstem injury was 0.310 ± 0.291% in rear impacts and 0.310 ± 0.170% in rollovers for unbelted occupants. The risk for brainstem injury increased with crash severity. The highest risk for brainstem injury was 3.54 ± 1.45% in crashes with >72 km/h (>45 mph) delta-V. Exponential functions fit the change in risk with delta-V. Eighteen NASS-CDS electronic cases showed that brainstem injury occurred in very severe collisions where the occupant experienced multiple injuries from intrusion or impact on vehicle structures stiffened by deformation.

CONCLUSIONS

The risk for brainstem injury in belted occupants has remained essentially constant over 20 years, whereas the risk for MAIS 4+F injury has declined 38.3%. The prevention of brainstem injuries must address the extreme speed of collisions and weight mismatches that overwhelm structures, seat belts, frontal airbags, side airbags, and curtains in modern vehicles.

Outcomes after concomitant traumatic brain injury and hemorrhagic shock: A secondary analysis from the Pragmatic, Randomized Optimal Platelets and Plasma Ratios trial

BACKGROUND

Often the clinician is faced with a diagnostic and therapeutic dilemma in patients with concomitant traumatic brain injury (TBI) and hemorrhagic shock (HS), as rapid deterioration from either can be fatal. Knowledge about outcomes after concomitant TBI and HS may help prioritize the emergent management of these patients. We hypothesized that patients with concomitant TBI and HS (TBI + HS) had worse outcomes and required more intensive care compared with patients with only one of these injuries.

METHODS

This is a post hoc analysis of the Pragmatic, Randomized Optimal Platelets and Plasma Ratios (PROPPR) trial. TBI was defined by a head Abbreviated Injury Scale score greater than 2. HS was defined as a base excess of -4 or less and/or shock index of 0.9 or greater. The primary outcome for this analysis was mortality at 30 days. Logistic regression, using generalized estimating equations, was used to model categorical outcomes.

RESULTS

Six hundred seventy patients were included. Patients with TBI + HS had significantly higher lactate (median, 6.3; interquartile range, 4.7-9.2) compared with the TBI group (median, 3.3; interquartile range, 2.3-4). TBI + HS patients had higher activated prothrombin times and lower platelet counts. Unadjusted mortality was higher in the TBI + HS (51.6%) and TBI (50%) groups compared with the HS (17.5%) and neither group (7.7%). Adjusted odds of death in the TBI and TBI + HS groups were 8.2 (95% confidence interval, 3.4-19.5) and 10.6 (95% confidence interval, 4.8-23.2) times higher, respectively. Ventilator, intensive care unit-free and hospital-free days were lower in the TBI and TBI + HS groups compared with the other groups. Patients with TBI + HS or TBI had significantly greater odds of developing a respiratory complication compared with the neither group.

CONCLUSION

The addition of TBI to HS is associated with worse coagulopathy before resuscitation and increased mortality. When controlling for multiple known confounders, the diagnosis of TBI alone or TBI+HS was associated with significantly greater odds of developing respiratory complications.

LEVEL OF EVIDENCE

Prognostic study, level II.

Development of thoracic injury risk functions for the THOR ATD

The Test Device for Human Occupant Restraint (THOR) 50th percentile male anthropomorphic test device (ATD) aims to improve the ability to predict the risk of chest injury to restrained automobile occupants by measuring dynamic chest deflection at multiple locations. This research aimed to describe the methods for developing a thoracic injury risk function (IRF) using the multi-point chest deflection metrics from the 50th percentile male THOR Metric ATD with the SD-3 shoulder and associating to post-mortem human subjects (PMHS) outcomes that were matched on identical frontal and frontal-oblique impact sled testing conditions. Several deflection metrics were assessed as potential predictor variables for AIS 3+ injury risk, including a combined metric, called PC Score, which was generated from a principal component analysis. A parametric survival analysis (specifically, accelerated failure time (AFT) with Weibull distribution) was assessed in the development of the IRF. Model fit was assessed using various modeling diagnostics, including the area under the receiver operating characteristic curve (AUC). Models based on resultant deflection consistently exhibited improved fit compared to models based on x-axis deflection or chord deflection. Risk functions for the THOR PC Score and C_max (maximum resultant deflection) were qualitatively equivalent, producing AUCs of 0.857 and 0.861, respectively. Adjusting for the potential confounding effects of age, AFT survival models with C_max or PC Score as the primary deflection metric resulted in the THOR injury risk models with the best combination of biomechanical appropriateness, potential utility and model fit, and may be recommended as injury predictors.

Factors associated with non-return to work in the severely injured victims 3 years after a road accident: A prospective study

Road accidents may impact victims' physical and/or mental health and socio-occupational life, particularly the capacity to return to work. The purpose of our study is to assess modifiable medical and socio-occupational factors of non-return to work in the severely injured 3 years after a road accident. Among1,168 road accidents casualties in the Rhône administrative Département of France followed for five years, 141 of the 222 severely injured (Maximal Abbreviated Injury Scale ≥ 3) aged more than 16 years who were in work at the time of the accident, reported whether they had returned to work in the 3 years following the accident. The subgroups of those who had (n=113) and had not returned to work (n=28) were compared for socio-occupational (gender, age, educational level, marital status, socio-occupational group) accident-related medical factors (type of road user, type of journey, responsibility in the accident, initial care) and post-accident medical factors (pain intensity, post-traumatic stress disorder, physical sequelae, quality of life) by using standardized tools. Severity of initial head, face and lower-limb injury, intense persistent pain, post-traumatic stress disorder, poor self-assessed quality of life and health status at 3 years were associated with non-return to work on univariate analysis. On multivariate analysis, severity of initial head and lower-limb injury, intense persistent pain at 3 years and post-traumatic stress disorder were significantly associated with non-return to work 3 years following severe road-accident injury. Post-traumatic stress disorder and chronic pain were essential modifiable medical determinants of non-return to work in the severely injured after a road accident: early adapted management could promote return to work in the severely injured. Improve early adapted treatment of pain and PTSD in the rehabilitation team should help the severely injured return to work following a road accident.

Risk factors affecting injury severity determined by the MAIS score

OBJECTIVE

Traffic crashes result in a loss of life but also impact the quality of life and productivity of crash survivors. Given the importance of traffic crash outcomes, the issue has received attention from researchers and practitioners as well as government institutions, such as the European Commission (EC). Thus, to obtain detailed information on the injury type and severity of crash victims, hospital data have been proposed for use alongside police crash records. A new injury severity classification based on hospital data, called the maximum abbreviated injury scale (MAIS), was developed and recently adopted by the EC. This study provides an in-depth analysis of the factors that affect injury severity as classified by the MAIS score.

METHOD

In this study, the MAIS score was derived from the International Classification of Diseases. The European Union adopted an MAIS score equal to or greater than 3 as the definition for a serious traffic crash injury. Gains are expected from using both police and hospital data because the injury severities of the victims are detailed by medical staff and the characteristics of the crash and the site of its occurrence are also provided. The data were obtained by linking police and hospital data sets from the Porto metropolitan area of Portugal over a 6-year period (2006-2011). A mixed logit model was used to understand the factors that contribute to the injury severity of traffic victims and to explore the impact of these factors on injury severity. A random parameter approach offers methodological flexibility to capture individual-specific heterogeneity. Additionally, to understand the importance of using a reliable injury severity scale, we compared MAIS with length of hospital stay (LHS), a classification used by several countries, including Portugal, to officially report injury severity. To do so, the same statistical technique was applied using the same variables to analyze their impact on the injury severity classified according to LHS.

RESULTS

This study showed the impact of variables, such as the presence of blood alcohol, the use of protection devices, the type of crash, and the site characteristics, on the injury severity classified according to the MAIS score. Additionally, the sex and age of the victims were analyzed as risk factors, showing that elderly and male road users are highly associated with MAIS 3+ injuries. The comparison between the marginal effects of the variables estimated by the MAIS and LHS models showed significant differences. In addition to the differences in the magnitude of impact of each variable, we found that the impact of the road environment variable was dependent on the injury severity classification.

CONCLUSIONS

The differences in the effects of risk factors between the classifications highlight the importance of using a reliable classification of injury severity. Additionally, the relationship between LHS and MAIS levels is quite different among countries, supporting the previous conclusion that bias is expected in the assessment of risk factors if an injury severity classification other than MAIS is used.

A Turbo Pascal Program to Convert Icd-9Cm Coded Injury Diagnoses into Injury Severity Scores: Icdtoais

Diagnoses of injuries as a result of trauma are commonly coded by means of the International Classification of Diseases (9th rev.) Clinical Modification (ICD-9CM). The Abbreviated Injury Scale (AIS) is frequently employed to assess the severity of injury per body region. The Injury Severity Score (ISS) is an over-all index or summary of the severity of injury. To compute one of these two types of scores the entire medical record of each patient must be examined. The program ICDTOAIS replaces the manual coding or translation between the two scores. The program converts the ICD-9CM coded diagnoses into AIS and ISS scores. The program also computes the maximum AIS (MAXAIS) per body region, enabling the researcher to assess the relative impact of the severity of trauma of different body regions in both morbidity and mortality studies. The program locates invalid ICD-9CM rubrics in the data file. ICDTOAIS may be employed as a program alone or as a procedure in database management systems (e.g., DBase III plus, DBase IV, or the different versions of FOXPRO). The program is written in Turbo Pascal, Version 6.

Improvement of Treatment Outcomes after Implementation of a Massive Transfusion Protocol: A Level I Trauma Center Experience

We assessed the effectiveness of the implementation of an institutional massive transfusion protocol (MTP) for resuscitation with a 1:1:1 transfusion ratio of packed red blood cell (PRBC), fresh frozen plasma, and platelet units. In a Level I trauma center database, all trauma admissions (2004-2012) that received massive transfusions (≥10 units PRBCs in the first 24 hours) were reviewed retrospectively. Demographic data, transfusion ratios, and outcomes were compared before (PRE) and after (POST) MTP implementation in May 2008. Age, sex, and mechanism of injury were similar between 239 PRE and 208 POST trauma patients requiring massive transfusion. Transfusion ratios of fresh frozen plasma:PRBC and platelet:PRBC increased after MTP implementation. Among survivors, MTP implementation shortened hospital length of stay from 31 to 26 days (P = 0.04) and intensive care unit length of stay from 31 to 26 days (P = 0.02). Linear regression identified treatment after (versus before) implementation of MTP as an independent predictor of decreased ventilator days after adjusting for age, Glasgow Coma Scale, and chest Abbreviated Injury Score (P < 0.0001). Modest improvement in ratios likely does not account for all significant improvements in outcomes. Implementing a standardized protocol likely impacts automation, efficiency, and/or timeliness of product delivery.

Transfusion of red blood cells in patients with traumatic brain injuries admitted to Canadian trauma health centres: a multicentre cohort study

BACKGROUND

Optimisation of healthcare practices in patients sustaining a traumatic brain injury is of major concern given the high incidence of death and long-term disabilities. Considering the brain's susceptibility to ischaemia, strategies to optimise oxygenation to brain are needed. While red blood cell (RBC) transfusion is one such strategy, specific RBC strategies are debated. We aimed to evaluate RBC transfusion frequency, determinants of transfusions and associated clinical outcomes.

METHODS

We conducted a retrospective multicentre cohort study using data from the National Trauma Registry of Canada. Patients admitted with moderate or severe traumatic brain injury to participating hospitals between April 2005 and March 2013 were eligible. Patient information on blood products, comorbidities, interventions and complications from the Discharge Abstract Database were linked to the National Trauma Registry data. Relative weights analyses evaluated the contribution of each determinant. We conducted multivariate robust Poisson regression to evaluate the association between potential determinants, mortality, complications, hospital-to-home discharge and RBC transfusion. We also used proportional hazard models to evaluate length of stay for time to discharge from ICU and hospital.

RESULTS

Among the 7062 patients with traumatic brain injury, 1991 patients received at least one RBC transfusion during their hospital stay. Female sex, anaemia, coagulopathy, sepsis, bleeding, hypovolemic shock, other comorbid illnesses, serious extracerebral trauma injuries were all significantly associated with RBC transfusion. Serious extracerebral injuries altogether explained 61% of the observed variation in RBC transfusion. Mortality (risk ratio (RR) 1.23 (95% CI 1.13 to 1.33)), trauma complications (RR 1.38 (95% CI 1.32 to 1.44)) and discharge elsewhere than home (RR 1.88 (95% CI 1.75 to 2.04)) were increased in patients who received RBC transfusion. Discharge from ICU and hospital were also delayed in transfused patients.

CONCLUSIONS

RBC transfusion is common in patients with traumatic brain injury and associated with unfavourable outcomes. Trauma severity is an important determinant of RBC transfusion. Prospective studies are needed to further evaluate optimal transfusion strategies in traumatic brain injury.

Small female rib cage fracture in frontal sled tests

OBJECTIVES

The 2 objectives of this study are to (1) examine the rib and sternal fractures sustained by small stature elderly females in simulated frontal crashes and (2) determine how the findings are characterized by prior knowledge and field data.

METHODS

A test series was conducted to evaluate the response of 5 elderly (average age 76 years) female postmortem human subjects (PMHS), similar in mass and size to a 5th percentile female, in 30 km/h frontal sled tests. The subjects were restrained on a rigid planar seat by bilateral rigid knee bolsters, pelvic blocks, and a custom force-limited 3-point shoulder and lap belt. Posttest subject injury assessment included identifying rib cage fractures by means of a radiologist read of a posttest computed tomography (CT) and an autopsy. The data from a motion capture camera system were processed to provide chest deflection, defined as the movement of the sternum relative to the spine at the level of T8.  A complementary field data investigation involved querying the NASS-CDS database over the years 1997-2012. The targeted cases involved belted front seat small female passenger vehicle occupants over 40 years old who were injured in 25 to 35 km/h delta-V frontal crashes (11 to 1 o'clock).

RESULTS

Peak upper shoulder belt tension averaged 1,970 N (SD = 140 N) in the sled tests. For all subjects, the peak x-axis deflection was recorded at the sternum with an average of -44.5 mm or 25% of chest depth. The thoracic injury severity based on the number and distribution of rib fractures yielded 4 subjects coded as Abbreviated Injury Scale (AIS) 3 (serious) and one as AIS 5 (critical). The NASS-CDS field data investigation of small females identified 205 occupants who met the search criteria. Rib fractures were reported for 2.7% of the female occupants.

CONCLUSIONS

The small elderly test subjects sustained a higher number of rib cage fractures than expected in what was intended to be a minimally injurious frontal crash test condition. Neither field studies nor prior laboratory frontal sled tests conducted with 50th percentile male PMHS predicted the injury severity observed. Although this was a limited study, the results justify further exploration of the risk of rib cage injury for small elderly female occupants.

Urban Bicyclist Trauma: Characterizing the Injuries, Consequent Surgeries, and Essential Sub-Specialties Providing Care

In the United States in 2013, nearly 500,000 bicyclists were injured and required emergency department care. The objectives of this study were to describe the types of injuries which urban bicyclists sustain, to analyze the number and type of surgeries required, and to better delineate the services providing care. This is an observational study of injured bicyclists presenting to a Level I trauma center between February 2012 and August 2014. Most data were collected within 24 hours of injury and included demographics, narrative description of the incident, results of initial imaging studies, Injury Severity Score, admission status, length of stay, surgical procedure, and admitting and discharging service. A total of 706 injured bicyclists were included in the study, and 187 bicyclists (26.4%) required hospital admission. Of those admitted, 69 (36.8%) required surgery. There was no difference in gender between those who required surgery and those who did not (P = 0.781). Those who required surgery were older (mean age 39.1 vs 34.1, P = 0.003). Patients requiring surgery had higher Abbreviated Injury Scores for head (P ≤ 0.001), face (P ≤ 0.001), abdomen (P = 0.012), and extremity (P ≤ 0.001) and higher mean Injury Severity Scores (12.6 vs 3.7, P < 0.001). Sixty-nine patients required surgery and were brought to the operating room 82 times for 89 distinct procedures. Lower extremity injuries were the reason for 43 (48.3%) procedures, upper extremity injuries for 14 (15.7%), and facial injuries for 15 (16.9%). Orthopedic surgery performed 50 (56.2%) procedures, followed by plastic surgery (15 procedures; 16.8%). Trauma surgeons performed five (5.6%) procedures in four patients. The majority of admitted patients were admitted and discharged by the trauma service (70.1%, 56.7%, respectively) followed by the orthopedics service (13.9%, 19.8%, respectively). Injured bicyclists represent a unique subset of trauma patients. Orthopedic surgeons are most commonly involved in their operative management and rarely are the operative skills of a general traumatologist required. From a resource perspective, it is more efficient to direct the inpatient care of bicyclists with single-system trauma to the appropriate surgical subspecialty service soon after appropriate initial evaluation and treatment by the trauma service.

Characterization of the occult nature of injury for frequently occurring motor vehicle crash injuries

BACKGROUND

Occult injuries are not easily detected and can be potentially life-threatening. The purpose of this study was to quantify the perceived occultness of the most frequent motor vehicle crash injuries according to emergency medical services (EMS) professionals.

STUDY DESIGN

An electronic survey was distributed to 1,125 EMS professionals who were asked to quantify the likelihood that first responders would miss symptoms related to a particular injury on a 5-point Likert scale. The Occult Score for each injury was computed from the average of all the survey responses and normalized to be a continuous metric ranging from 0 to 1 where 0 is a non-occult (highly apparent on initial presentation) injury and 1 is an occult (unapparent on initial presentation) injury.

RESULTS

Overall, 110,671 survey responses were collected. The Occult Score ranged from 0 to 1 with a mean, median, and standard deviation of 0.443, 0.450, and 0.233, respectively. When comparing the Occult Score of an injury to its corresponding AIS severity, there was no relationship between the metrics. When stratifying by body region, injury type, and AIS severity, it was evident that AIS 2-4 abdominal injuries with lacerations, hemorrhage, or contusions were perceived as the most occult injuries.

CONCLUSIONS

Timely triage is key to reduce the morbidity and mortality associated with occult injuries. The Occult Score developed in this study to describe the predictability of an injury in a motor vehicle crash will be used as part of a larger effort, including incorporation into an advanced automatic crash notification (AACN) algorithm to detect crash conditions associated with a patient's need for prompt treatment at a trauma center.

Injury severity measures for predicting return-to-work after a traumatic brain injury

This study compared the ability of five injury severity measures, namely the Abbreviated Injury Scale to the Head (AIS-H), Glasgow Coma Scale (GCS), Glasgow Outcome Scale (GOS), Extended Glasgow Outcome Scale (GOSE), and Injury Severity Score (ISS), to predict return-to-work after a traumatic brain injury (TBI). Furthermore, factors potentially associated with return-to-work were investigated. In total, 207 individuals aged ≤65 years newly diagnosed with a TBI and employed at the time of injury were recruited and followed-up for 1year by telephone every 3 months. A bivariate proportional hazards model analysis revealed that all five injury severity measures were significantly associated with return-to-work after a TBI. The AIS-H and non-head ISS explained 23.8% of the variation in the duration of returning to work from discharge after hospitalization for a TBI; similarly, the GCS, GOS, GOSE, and ISS respectively accounted for 4.7%, 21.4%, 12.9%, and 48.4% of the variation. A multivariable analysis revealed that individuals with higher injury severity as measured by the ISS (hazard ratio [HR], 0.94; 95% confidence interval [CI], 0.92-0.97), a lack of autonomy in transportation (HR, 2.55; 95% CI, 1.23-5.32), cognitive impairment (HR, 0.47; 95% CI, 0.28-0.79), and depression (HR, 0.97; 95% CI, 0.95-0.99) were significantly less likely to be employed after a TBI. In conclusion, of the five injury severity measures, the ISS may be the most capable measure of predicting return-to-work after a TBI. In addition to injury severity, autonomy in transportation, cognitive function, and the depressive status may also influence the employment status during the first year after a TBI.

A Pediatric Application of the STRAC Regional Hospital Trauma Registry Database: Pediatric Trauma Deaths in South Central Texas During 2004-2013

The purpose of this study was to define the demographics of pediatric traumatic injuries and to understand the predictive value of injury type, prehospital, and emergency department (ED) data regarding the mortality of pediatric trauma patients (&lt;14 years of age) in South Central Texas. We report a retrospective review of pediatric trauma patients presenting to Trauma Service Area P in South Central Texas during 2004-2013. The primary outcome was mortality; secondary outcomes were ventilator days, hospital days, and intensive care unit stay. Demographics, Abbreviated Injury Score (AIS) codes, ICD-9 codes, transport times, Emergency Medical Services (EMS) vital signs en route and on arrival to the emergency department (ED), and outcomes were evaluated. A total of 8004 traumatically injured children presented to EDs in South Central Texas during the study period; 4109 of these presented via EMS. Most patients were Hispanic and male. Distribution was even across age groups. Overall mortality was 2%, and the mortality of those arriving by EMS was 3.7%. Abnormal vital signs and Glasgow Coma Score upon presentation to both EMS and the ED were strongly associated with mortality. Increased Injury Severity Score, the need for transfusion in the ED, and increased maximal AIS were also strongly associated with mortality. African American race was associated with increased mortality, although transport time and age were not. Most injuries overall were caused by motor vehicle collisions; however, burns and falls were most common in infants. The most lethal injuries were caused by firearms (mostly seen in preteens) and assaults (mostly seen in infants). This analysis of injured children in Southwest Texas offers insight into areas of needed quality improvement in the trauma system and potential areas to focus prevention efforts.

Outcomes in Trauma Patients with Isolated Epidural Hemorrhage: A Single-Institution Retrospective Cohort Study

The type, location, and size of intracranial hemorrhage are known to be associated with variable outcomes in patients with traumatic brain injury (TBI). The aim of our study was to assess the outcomes in patients with isolated epidural hemorrhage (EDH) based on the location of EDH. We performed a 3-year (2010-2012) retrospective chart review of the patients with TBI in our level 1 trauma center. Patients with an isolated EDH on initial head CT scan were included. Patients were divided into four groups based on the location of EDH: frontal, parietal, temporal, and occipital. Differences in demographics and outcomes between the four groups were assessed. Outcome measures were progression on repeat head CT and neurosurgical intervention (NI). A total of 76 patients were included in this study. The mean age was 20.6 ± 15.2 years, 68.4 per cent were male, median Glasgow Coma Scale (GCS) score 15 (13-15), and median head Abbreviated Injury Scale score was 3 (2-4). About 32.9 per cent patients (n = 25) had frontal EDH, 26.3 per cent (n = 20) had temporal EDH, 10.5 per cent (n = 8) had occipital EDH, while the remaining 30.3 per cent (n = 23) had parietal EDH. The overall progression rate was 21.1 per cent (n = 12) and NI rate was 29 per cent (n = 22). There was no difference in the outcome of patients based on location of EDH. Patients with NI had a longer hospital length of stay (P = 0.02) and longer intensive care unit length of stay (P = 0.05). The incidence of isolated EDH is low in patients with blunt TBI. Patients with isolated EDH undergoing NI have longer hospital stays compared to patients without NI. Further investigation is warranted to identify factors associated with need for NI and adverse outcomes in the cohort of patients with isolated EDH.

An Analysis of Beta-Blocker Administration Pre-and Post-Traumatic Brain Injury with Subanalyses for Head Injury Severity and Myocardial Injury

A growing body of literature indicates that beta-blocker administration after traumatic brain injury (TBI) is cerebroprotective, limiting secondary injury; however, the effects of preinjury beta blocker status remain poorly understood. We sought to characterize the effects of pre- and postinjury beta-blocker administration on mortality with subanalyses accounting for head injury severity and myocardial injury. In a Level II trauma center, all admissions of patients ≥18 years with a head Abbreviated Injury Scale Score ≥2, Glasgow Coma Scale ≤13 from May 2011 to May 2013 were queried. Demographic, injury-specific, and outcome variables were analyzed using univariate analyses. Subsequent multivariate analyses were conducted to determine adjusted odds of mortality for beta-blocker usage controlling for age, Injury Severity Score, head Abbreviated Injury Scale, arrival Glasgow Coma Scale, ventilator use, and intensive care unit stay. A total of 214 trauma admissions met inclusion criteria: 112 patients had neither pre- nor postinjury beta-blocker usage, 46 patients had preinjury beta-blocker usage, and 94 patients had postinjury beta-blocker usage. Both unadjusted and adjusted odds ratios of preinjury beta-blocker were insignificant with respect to mortality. However, postinjury in-hospital administration of beta blockers was found to significantly in the decrease of mortality in both univariate (P = 0.002) and multivariate analyses (P = 0.001). Our data indicate that beta-blocker administration post-TBI in hospital reduces odds of mortality; however, preinjury beta-blocker usage does not. Additionally, myocardial injury is a useful indicator for beta-blocker administration post-TBI. Further research into which beta blockers confer the best benefits as well as the optimal period of beta-blocker administration post-TBI is recommended.

Epidemiology of Severely and Fatally Injured Patients in Western Part of Norway

Background and Aims:

Analysis of the injury mechanism and characteristics of severely and fatally injured patients in the western part of Norway.

Material and Methods:

We did a prospective registration of all severely injured patients hospitalized during a three-year period. The files of severely injured patients that died at scene or during transport were retrospectively retrieved from the Forensic Department. A total of 558 patients with an Injury Severity Score > 15 were included.

Results:

Four-hundred-forty-four men (79.6 %) and 114 women (20.4 %) with a median age of 36 and 51.5 years respectively were included. The proportion of female patients older than 80 years were 19.3 % compared to 5.6 % for men. A total of 215 (38.5 %) patients died and 149 (69.3 %) of these patients died on scene or during transport. The incidence of severely injured patients in Hordaland County was 30 per 100 000 inhabitants per year. The incidence was lowest among children below 5 years (7/100 000/year) and highest among persons older than 80 years (95/100 000/year). Men had a 3.8 times greater risk of getting seriously injured compared to women. Road traffic accidents were the cause of the injuries in 235 (42.1%) patients and 35.8% of these patients died. A total of 215 (38.5 %) patients were injured due to falls and 30.2 % of these patients died. Patients who had sustained falls were significantly older than patents with other injury mechanisms (p < 0.001, CI = 13.0–20.2). The proportion of patients with penetrating injuries was 7.3 %.

Conclusion:

The incidence of severely injured patients was 30/100000/year. Men and elderly people had a higher risk of getting severely injured. Falls were the dominating injury mechanism among elderly.

Age-Specific Injury Risk Curves for Distributed, Anterior Thoracic Loading of Various Sizes of Adults Based on Sternal Deflections

Injury Risk Curves are developed from cadaver data for sternal deflections produced by anterior, distributed chest loads for a 25, 45, 55, 65 and 75 year-old Small Female, Mid-Size Male and Large Male based on the variations of bone strengths with age. These curves show that the risk of AIS ≥ 3 thoracic injury increases with the age of the person. This observation is consistent with NASS data of frontal accidents which shows that older unbelted drivers have a higher risk of AIS ≥ 3 chest injury than younger drivers.

Functional recovery patterns in seriously injured automotive crash victims

OBJECTIVE

The functional capacity index (FCI) is designed to predict functional loss 12 months post-injury for each injury in the 2008 Abbreviated Injury Scale (AIS) manual on a scale from 0 (death) to 100 (full recovery), but FCI has never been validated. This study compared FCI predicted loss with patient-reported 12-month outcomes as measured through the Short Form 36 (SF-36) health assessment survey.

METHODS

Using follow-up data collected on 2,858 adult car crash occupants in the Crash Injury Research and Engineering Network (CIREN) database, we compared FCI predicted outcomes to occupants' Physical Component Summary (PCS) scores, which are weighted averages of the SF-36 items addressing physical function. Our analyses included descriptive statistics, plots of typical recovery patterns, and a mixed effects regression model that describes PCS as a function of FCI, demographics, comorbidities, and injury pattern while also adjusting for the occupants' pre-crash physical capabilities. We further examined injuries in patients who report a significant drop in PCS 12 months post-crash despite being predicted to fully recover.

RESULTS

At baseline, the CIREN population exhibited PCS scores similar to the overall population (mean = 51.1, SD = 10.3). Twelve months post-crash, occupants with predicted impairment (FCI < 100) report a substantial decrease in physical function, and those who were predicted to fully recover still report some, albeit less, impairment. In the multivariate mixed-effects regression model, FCI is a strongly significant (P-value <.0001) predictor of PCS, with each 1-point drop in FCI predicting a 0.27-point drop in PCS. Maximum AIS severities in the head, spine, and lower extremity body regions were also significantly associated with PCS (P-values <.05). Among occupants who were expected to fully recover but who report a significant drop in PCS at 12 months, spinal fractures without cord involvement account for 5 of the 10 most common AIS 2+ injuries.

CONCLUSIONS

FCI was associated with 12-month outcomes but may not adequately describe the recovery from some head, spine, and lower extremity injuries. Some occupants who were expected to recover still report functional loss 12 months post-injury.

Functional outcomes of motor vehicle crash head injuries in pediatric and adult occupants

OBJECTIVE

The objective of the study was to develop a disability-based metric for motor vehicle crash (MVC) injuries, with a focus on head injuries, and compare the functional outcomes between the pediatric and adult populations.

METHODS

Disability risk (DR) was quantified using Functional Independence Measure (FIM) scores within the National Trauma Data Bank-Research Data System (NTDB-RDS) for the top 95% most frequently occurring Abbreviated Injury Scale (AIS) 3, 4, and 5 head injuries in NASS-CDS 2000-2011. Pediatric (ages 7-18), adult (19-45), middle-aged (46-65), and older adult (66+) patients with an FIM score available who were alive at discharge and had an AIS 3, 4, or 5 injury were included in the study. The NTDB-RDS contains a truncated form of the FIM instrument, including 3 items (self-feed, locomotion, and verbal expression), each graded on a scale of 1 (full functional dependence) to 4 (full functional independence). Patients within each age group were classified as disabled or not disabled based on the FIM scale. The DR was calculated for each age group by dividing the number of patients who sustained a specific injury and were disabled by the number of patients who sustained the specific injury. To account for the impact of more severe associated coinjuries, a maximum AIS (MAIS) adjusted DR (DRMAIS) was also calculated for each injury. DR and DRMAIS ranged from 0 (0% disability risk) to 1 (100% disability risk).

RESULTS

An analysis of the most frequent FIM components associated with disabling MVC head injuries revealed that disability across all 3 items (self-feed, locomotion, and expression) was the most frequent for pediatric and adult patients. Only locomotion was the most frequent for middle-aged and older adults. The mean DRMAIS for MVC head injuries was 35% for pediatric patients, 36% for adults, 38% for middle-aged adults, and 44% for older adults. Further analysis was conducted by grouping the head injuries into 8 groups based on the structure of injury and injury type. The pediatric population possessed higher DRMAIS values for brain stem injuries as well as loss of consciousness injuries. Older adults possessed higher DRMAIS values for contusion/hemorrhage injuries, epidural hemorrhage, intracerebral hemorrhage, skull fracture, and subdural/subarachnoid hemorrhage.

CONCLUSION

At-risk populations such as pediatric and older adult patients possessed higher DRMAIS values for different head injuries. Disability in pediatric patients is critical due to loss of quality life years. Disability risk can supplement severity metrics to improve the ability of such metrics to discriminate the severity of different injuries that do not lead to death. Understanding of age-related differences in injury outcomes when compared to adults could inform future age-specific modifications to the AIS.

Changing threshold for AIS scores of thoracolumbar compression fractures

BACKGROUND

The Abbreviated Injury Scale (AIS) is an anatomical-based coding system created by the Association for the Advancement of Automotive Medicine, utilized to classify and code injuries resulting from trauma, in order of severity. According to the latest version, all Thoraco-Lumbar Compression Fractures (TLCF), even without injury to other spine components and with >20% loss of height, were branded AIS 3 injuries, reflecting a serious threat to life or permanent disability. Advances in spine imaging, recent biomechanical studies, and long-term outcomes research offer the opportunity to consider these injuries differently.

OBJECTIVE

To re-evaluate the percent compression threshold of TLCF of the spine from motor vehicle crashes (MVC) for serious risk to life identified as surgical treatment, delineating a reliable cut-off for fracture severity and morbidity. Little national data considers degree of compression and provides adequate followup imaging to determine degree of compression, justifying this effort.

METHODS

Charts and radiographs of patients admitted to our institution due to vehicle crashes with isolated (vertebral body only) TLCF between 2008 and 2015 were reviewed. Data were collected on degree of compression, treatment, and long-term outcomes to determine the threshold of permanent injury. Vertebral bodies at the level of fracture were measured both anteriorly and posteriorly, and compared to adjacent segments; percentage compression was calculated.

RESULTS

1470 patient records with diagnoses of spine trauma were reviewed; 695 isolated compression fractures were identified, of which 194 were in vehicle crashes and had adequate imaging and follow-up. Ages ranged from 19 to 82, with a male: female ratio of 60:40. No patient with vertebral body compression of less than 30% underwent surgery unless presenting with a neurological deficit. All 22 surgical patients demonstrated significant retropulsion of bone into the spinal canal. Five surgical patients suffered eight complications; there were no adverse outcomes in the nonsurgical group.

CONCLUSIONS

These results are consistent with evolving clinical thinking, resulting in decreasing surgical incidence and orthosis use. Our data strongly suggests that isolated compression fractures in the absence of neurologic deficit or severe cord compression due to retropulsed bone are self-limiting. Therefore, the AIS scores for these common injuries could be reconsidered and reflect their relatively benign outlook.

Injury severity of pedestrians, bicyclists and motorcyclists resulting from crashes with reversing cars

OBJECTIVE

Pedestrians, bicyclists and motorcyclists can suffer serious injury in road traffic crashes. To date, no studies examine the injury severity within this vulnerable cohort following collisions with reversing cars.

MATERIAL AND METHODS

Our institution prospectively maintains a database including medical and technical information regarding traffic accidents in our area, including urban and suburban regions. In a retrospective review of this database, the authors describe the injury severity of pedestrians, bicyclists and motorcyclists following traffic crashes involving reversing cars. Injury severity was described using the abbreviated injury scale (AIS) as well as the maximum abbreviated injury scale (MAIS).

RESULTS

This study included 234 crashes occurring between 1999 and 2012. The lower extremity was injured most often while also suffering more severe injuries with a median AIS of 1 compared to 0 in all other documented body regions. The upper extremity was injured second most often. AIS ranging from 4 to 6 were infrequent. AIS 3 however, was documented for the legs in 4.3% of patients. MAIS 0, 1, 2, 3, 5 and 9 were found in 1, 164, 46, 14, 1, and 8 patients in the study cohort, respectively. Pedestrians and motorcyclists were seriously injured in 9.1% and 9.6% of cases, respectively. In contrast, no bicyclists suffered serious injuries. As to the zone of impact, most collisions occurred at the rear center of the vehicle (35%) followed by rear left (26%), rear right (20%), side rear (11%), side center (4%) and side front (3%). 204 (87.2%) collisions occurred during the day, 19 (8.1%) at night and 11 (4.7%) at twilight. Speed was similar in crashes involving pedestrians, bicyclists and motorcyclists, being as high as 7.0±3.6, 7.0±4.0 and 7.9±4.2km/h respectively.

CONCLUSIONS

This is the first study that analyzes injury severity among these vulnerable road users following collisions with reversing vehicles. The majority of collisions occur at low impact speed during the day. Most injuries resulting from these collisions are not serious, however pedestrians are at greatest risk of severe injury to any body region. The lower extremities suffer the most serious and frequent injuries within this cohort.

Development of an expert based ICD-9-CM and ICD-10-CM map to AIS 2005 update 2008

OBJECTIVE

This article describes how maps were developed from the clinical modifications of the 9th and 10th revisions of the International Classification of Diseases (ICD) to the Abbreviated Injury Scale 2005 Update 2008 (AIS08). The development of the mapping methodology is described, with discussion of the major assumptions used in the process to map ICD codes to AIS severities. There were many intricacies to developing the maps, because the 2 coding systems, ICD and AIS, were developed for different purposes and contain unique classification structures to meet these purposes.

METHODS

Experts in ICD and AIS analyzed the rules and coding guidelines of both injury coding schemes to develop rules for mapping ICD injury codes to the AIS08. This involved subject-matter expertise, detailed knowledge of anatomy, and an in-depth understanding of injury terms and definitions as applied in both taxonomies. The official ICD-9-CM and ICD-10-CM versions (injury sections) were mapped to the AIS08 codes and severities, following the rules outlined in each coding manual. The panel of experts was composed of coders certified in ICD and/or AIS from around the world. In the process of developing the map from ICD to AIS, the experts created rules to address issues with the differences in coding guidelines between the 2 schemas and assure a consistent approach to all codes.

RESULTS

Over 19,000 ICD codes were analyzed and maps were generated for each code to AIS08 chapters, AIS08 severities, and Injury Severity Score (ISS) body regions. After completion of the maps, 14,101 (74%) of the eligible 19,012 injury-related ICD-9-CM and ICD-10-CM codes were assigned valid AIS08 severity scores between 1 and 6. The remaining 4,911 codes were assigned an AIS08 of 9 (unknown) or were determined to be nonmappable because the ICD description lacked sufficient qualifying information for determining severity according to AIS rules. There were also 15,214 (80%) ICD codes mapped to AIS08 chapter and ISS body region, which allow for ISS calculations for patient data sets.

CONCLUSION

This mapping between ICD and AIS provides a comprehensive, expert-designed solution for analysts to bridge the data gap between the injury descriptions provided in hospital codes (ICD-9-CM, ICD-10-CM) and injury severity codes (AIS08). By applying consistent rules from both the ICD and AIS taxonomies, the expert panel created these definitive maps, which are the only ones endorsed by the Association for the Advancement of Automotive Medicine (AAAM). Initial validation upheld the quality of these maps for the estimation of AIS severity, but future work should include verification of these maps for MAIS and ISS estimations with large data sets. These ICD-AIS maps will support data analysis from databases with injury information classified in these 2 different systems and open new doors for the investigation of injury from traumatic events using large injury data sets.

Lower limb and associated injuries in frontal-impact road traffic collisions

OBJECTIVES

To study the relationship between severity of injury of the lower limb and severity of injury of the head, thoracic, and abdominal regions in frontal-impact road traffic collisions.

METHODS

Consecutive hospitalised trauma patients who were involved in a frontal road traffic collision were prospectively studied over 18 months. Patients with at least one Abbreviated Injury Scale (AIS) ≥3 or AIS 2 injuries within two AIS body regions were included. Patients were divided into two groups depending on the severity of injury to the head, chest or abdomen. Low severity group had an AIS < 2 and high severity group had an AIS ≥ 2. Backward likelihood logistic regression models were used to define significant factors affecting the severity of head, chest or abdominal injuries.

RESULTS

Eighty-five patients were studied. The backward likelihood logistic regression model defining independent factors affecting severity of head injuries was highly significant (p =0.01, nagelkerke r square = 0.1) severity of lower limb injuries was the only significant factor (p=0.013) having a negative correlation with head injury (Odds ratio of 0.64 (95% CI: 0.45-0.91).

CONCLUSION

Occupants who sustain a greater severity of injury to the lower limb in a frontal-impact collision are likely to be spared from a greater severity of head injury.

Discovering the truth about life after discharge: Long-term trauma-related mortality

BACKGROUND

Outcome after traumatic injury has typically been limited to the determination at time of discharge or brief follow-up. This study investigates the natural history of long-term survival after trauma.

METHODS

All highest-level activation patients prospectively enrolled in an ongoing cohort study from 2005 to 2012 were selected. To allow for long-term follow-up, patients had to be enrolled at least 1 year before the latest available data from the National Death Index (NDI, 2013). Time and cause of mortality was determined based on death certificates. Survival status was determined by the latest date of either care in our institution or NDI query. Kaplan-Meier curves were created stratified for Injury Severity Score (ISS). Survival was compared with estimated actuarial survival based on age, sex, and race.

RESULTS

A total of 908 highest-level activation patients (median ISS, 18) were followed up for a median 1.7 years (interquartile range 1.0-2.9; maximum, 9.8 years). Survival data were available on 99.8%. Overall survival was 73% (663 of 908). For those with at least 2-year follow-up, survival was only 62% (317 of 509). Severity of injury predicted long-term survival (p < 0.0001) with those having ISS of 25 or greater with the poorest outcome (57% survival at 5 years). For all ISS groups, survival was worse than predicted actuarial survival (p < 0.001). When excluding early deaths (≤30 days), observed survival was still significantly lower than estimated actuarial survival (p < 0.002). Eighteen percent (44 of 245 deaths) of all deaths occurred after 30 days. Among late deaths, 53% occurred between 31 days and 1 year after trauma. Trauma-related mortality was the leading cause of postdischarge death, accounting for 43% of the late deaths.

CONCLUSION

Postdischarge deaths represent a significant percentage of total trauma-related mortality. Despite having "survived" to leave the hospital, long-term survival was worse than predicted actuarial survival, suggesting that the mortality from injury does not end at "successful" hospital discharge.

LEVEL OF EVIDENCE

Prognostic study, level III.

Improving early identification of the high-risk elderly trauma patient by emergency medical services

STUDY OBJECTIVE

We sought to (1) define the high-risk elderly trauma patient based on prognostic differences associated with different injury patterns and (2) derive alternative field trauma triage guidelines that mesh with national field triage guidelines to improve identification of high-risk elderly patients.

METHODS

This was a retrospective cohort study of injured adults ≥65 years transported by 94 EMS agencies to 122 hospitals in 7 regions from 1/1/2006 through 12/31/2008. We tracked current field triage practices by EMS, patient demographics, out-of-hospital physiology, procedures and mechanism of injury. Outcomes included Injury Severity Score≥16 and specific anatomic patterns of serious injury using abbreviated injury scale score ≥3 and surgical interventions. In-hospital mortality was used as a measure of prognosis for different injury patterns.

RESULTS

33,298 injured elderly patients were transported by EMS, including 4.5% with ISS≥16, 4.8% with serious brain injury, 3.4% with serious chest injury, 1.6% with serious abdominal-pelvic injury and 29.2% with serious extremity injury. In-hospital mortality ranged from 18.7% (95% CI 16.7-20.7) for ISS≥16 to 2.9% (95% CI 2.6-3.3) for serious extremity injury. The alternative triage guidelines (any positive criterion from the current guidelines, GCS≤14 or abnormal vital signs) outperformed current field triage practices for identifying patients with ISS≥16: sensitivity (92.1% [95% CI 89.6-94.1%] vs. 75.9% [95% CI 72.3-79.2%]), specificity (41.5% [95% CI 40.6-42.4%] vs. 77.8% [95% CI 77.1-78.5%]). Sensitivity decreased for individual injury patterns, but was higher than current triage practices.

CONCLUSIONS

High-risk elderly trauma patients can be defined by ISS≥16 or specific non-extremity injury patterns. The field triage guidelines could be improved to better identify high-risk elderly trauma patients by EMS, with a reduction in triage specificity.

A New Method to Classify Injury Severity by Diagnosis: Validation Using Workers' Compensation and Trauma Registry Data

PURPOSE

Acute work-related trauma is a leading cause of death and disability among U.S. workers. Existing methods to estimate injury severity have important limitations. This study assessed a severe injury indicator constructed from a list of severe traumatic injury diagnosis codes previously developed for surveillance purposes. Study objectives were to: (1) describe the degree to which the severe injury indicator predicts work disability and medical cost outcomes; (2) assess whether this indicator adequately substitutes for estimating Abbreviated Injury Scale (AIS)-based injury severity from workers' compensation (WC) billing data; and (3) assess concordance between indicators constructed from Washington State Trauma Registry (WTR) and WC data.

METHODS

WC claims for workers injured in Washington State from 1998 to 2008 were linked to WTR records. Competing risks survival analysis was used to model work disability outcomes. Adjusted total medical costs were modeled using linear regression. Information content of the severe injury indicator and AIS-based injury severity measures were compared using Akaike Information Criterion and R(2).

RESULTS

Of 208,522 eligible WC claims, 5 % were classified as severe. Among WC claims linked to the WTR, there was substantial agreement between WC-based and WTR-based indicators (kappa = 0.75). Information content of the severe injury indicator was similar to some AIS-based measures. The severe injury indicator was a significant predictor of WTR inclusion, early hospitalization, compensated time loss, total permanent disability, and total medical costs.

CONCLUSIONS

Severe traumatic injuries can be directly identified when diagnosis codes are available. This method provides a simple and transparent alternative to AIS-based injury severity estimation.

Validation of a base deficit-based trauma prediction model and comparison with TRISS and ASCOT

BACKGROUND

Base deficit provides a more objective indicator of physiological stress following injury as compared with vital signs constituting the revised trauma score (RTS). We have previously developed a base deficit-based trauma survival prediction model [base deficit and injury severity score model (BISS)], in which RTS was replaced by base deficit as a measurement of physiological imbalance.

PURPOSE

To externally validate BISS in a large cohort of trauma patients and to compare its performance with established trauma survival prediction models including trauma and injury severity score (TRISS) and a severity characterization of trauma (ASCOT). Moreover, we examined whether the predictive accuracy of BISS model could be improved by replacement of injury severity score (ISS) by new injury severity score (NISS) in the BISS model (BNISS).

METHODS

In this retrospective, observational study, clinical data of 3737 trauma patients (age ≥15 years) admitted consecutively from 2003 to 2007 were obtained from a prospective trauma registry to calculate BISS, TRISS, and ASCOT models. The models were evaluated in terms of discrimination [area under curve (AUC)] and calibration.

RESULTS

The in-hospital mortality rate was 8.1 %. The discriminative performance of BISS to predict survival was similar to that of TRISS and ASCOT [AUCs of 0.883, 95 % confidence interval (CI) 0.865-0.901 for BISS, 0.902, 95 % CI 0.858-0.946 for TRISS and 0.864, 95 % CI 0.816-0.913 for ASCOT]. Calibration tended to be optimistic in all three models. The updated BNISS had an AUC of 0.918 indicating that substitution of ISS with NISS improved model performance.

CONCLUSIONS

The BISS model, a base deficit-based trauma model for survival prediction, showed equivalent performance as compared with that of TRISS and ASCOT and may offer a more simplified calculation method and a more objective assessment. Calibration of BISS model was, however, less good than that of other models. Replacing ISS by NISS can considerably improve model accuracy, but further confirmation is needed.

Oblique Loading in Post Mortem Human Surrogates from Vehicle Lateral Impact Tests using Chestbands

While numerous studies have been conducted to determine side impact responses of Post Mortem Human Surrogates (PMHS) using sled and other equipment, experiments using the biological surrogate in modern full-scale vehicles are not available. The present study investigated the presence of oblique loading in moving deformable barrier and pole tests. Threepoint belt restrained PMHS were positioned in the left front and left rear seats in the former and left front seat in the latter condition and tested according to consumer testing protocols. Three chestbands were used in each specimen (upper, middle and lower thorax). Accelerometers were secured to the skull, shoulder, upper, middle and lower thoracic vertebrae, sternum, and sacrum. Chestband signals were processed to determine magnitudes and angulations of peak deflections. The magnitude and timing of various signal peaks are given. Vehicle accelerations, door velocities, and seat belt loads are also given. Analysis of deformation contours, peak deflections, and angulations indicated that the left rear seated specimen were exposed to anterior oblique loading while left front specimens in both tests sustained essentially pure lateral loading to the torso. These data can be used to validate human body computational models. The occurrence of oblique loading in full-scale testing, hitherto unrecognized, may serve to stimulate the exploration of its role in injuries to the thorax and lower extremities in modern vehicles. It may be important to continue research in this area because injury metrics have a lower threshold for angled loading.

Obesity Increases Early Complications After High-Energy Pelvic and Acetabular Fractures

Elevated body mass index has been identified as a potential risk factor for complications in operatively treated pelvic trauma. Although obesity is an independent risk factor for morbidity and mortality following high-energy blunt force trauma, there is little information on the immediate complications following isolated pelvic and acetabular fractures in obese patients with trauma. The authors hypothesized that obesity (body mass index ≥30 kg/m(2)) is a risk factor for complications in both operative and nonoperative pelvic and acetabular fractures. The authors conducted a 5-year retrospective data collection of all patients with isolated pelvic and acetabular fractures presenting to a Level I trauma center, excluding pediatric (age <18 years) patients, those with ballistic injuries, and those with concomitant long bone fractures or an Abbreviated Injury Scale score of greater than 2 in any other body region. Complications during the immediate hospitalization period were identified by the institution's Trauma Registry of the American College of Surgeons database, including wound infection, dehiscence, deep venous thrombosis, pulmonary embolus, pneumonia, and development of decubitus ulcers. Mean body mass index was 27.4 ± 6.8 kg/m(2), with 68 (27.0%) obese patients. Mean body mass index of patients with complications was significantly higher (31.9 ± 9.5 vs 27.0 ± 6.5 kg/m(2); P=.001). Logistic regression showed that obesity was a significant risk factor for complications (odds ratio, 2.87; 95% confidence interval, 1.02-8.04), after adjusting for age (odds ratio, 1.03; 95% confidence interval, 1.01-1.06) and Injury Severity Score (odds ratio, 1.20; 95% confidence interval, 1.10-1.32). Obesity is associated with increasing complications following operative fixation of pelvic and acetabular fractures. However, it is important to recognize that even nonoperative management of pelvic and acetabular fractures in obese patients can have early complications. This study showed a significant obesity-related risk of complications after trauma in both operative and nonoperative pelvic injuries.

Health Care Costs 1 Year After Pediatric Traumatic Brain Injury

OBJECTIVES

This study sought to estimate total health care costs for mild, moderate, and severe pediatric traumatic brain injury (TBI) and to compare individual- and population-level costs across levels of TBI severity.

METHODS

Using 2007 to 2010 MarketScan Commercial Claims and Encounters data, we estimated total quarterly health care costs 1 year after TBI among enrollees (aged < 18 years). We compared costs across levels of TBI severity using generalized linear models.

RESULTS

Mild TBI accounted for 96.6% of the 319 103 enrollees with TBI; moderate and severe TBI accounted for 1.7% and 1.6%, respectively. Adjusted individual health care costs for moderate and severe TBI were significantly higher than mild TBI in the year after injury (P < .01). At the population level, moderate and severe TBI costs were 88% and 75% less than mild TBI, respectively.

CONCLUSIONS

Individually, moderate and severe TBI initially generated costs that were markedly higher than those of mild TBI. At the population level, costs following mild TBI far exceeded those of more severe cases, a result of the extremely high population burden of mild TBI.

Patient- and Community-Level Sociodemographic Characteristics Associated with Emergency Department Visits for Childhood Injury

OBJECTIVE

To examine pediatric emergency department (ED) visits over 5 years, trends in injury severity, and associations between injury-related ED visit outcome and patient and community-level sociodemographic characteristics.

STUDY DESIGN

Retrospective analysis of administrative data provided to the Pediatric Emergency Care Applied Research Network Core Data Project, 2004-2008. Home addresses were geocoded to determine census block group and associated sociodemographic characteristics. Maximum Abbreviated Injury Scale severity and Severity Classification System scores were calculated. Generalized estimating equations were used to test for associations between sociodemographic characteristics and admission or transfer among injury-related ED visits.

RESULTS

Overall ED visits and injury-related visits increased from 2004 to 2008 at study sites. Of 2,833676 successfully geocoded visits, 700,821 (24.7%) were injury-related. The proportion of higher severity injury-related visits remained consistent. Nearly 10% of injury-related visits resulted in admission or transfer each year. After adjusting for age, sex, payer, and injury severity, odds of admission or transfer were lower among minority children and children from areas with moderate and high prevalence of poverty.

CONCLUSIONS

Pediatric injury-related ED visits to included sites increased over the study period while injury severity, anticipated resource utilization, and visit outcomes remained stable, with low rates of admission or transfer. Sociodemographic differences in injury-related visits and ED disposition were apparent. ED-based injury surveillance is essential to understand disparities, inform targets for prevention programs, and reduce the overall burden of childhood injuries.

Rear seat safety: Variation in protection by occupant, crash and vehicle characteristics

OBJECTIVES

Current information on the safety of rear row occupants of all ages is needed to inform further advances in rear seat restraint system design and testing. The objectives of this study were to describe characteristics of occupants in the front and rear rows of model year 2000 and newer vehicles involved in crashes and determine the risk of serious injury for restrained crash-involved rear row occupants and the relative risk of fatal injury for restrained rear row vs. front passenger seat occupants by age group, impact direction, and vehicle model year.

METHOD

Data from the National Automotive Sampling System Crashworthiness Data System (NASS-CDS) and Fatality Analysis Reporting System (FARS) were queried for all crashes during 2007-2012 involving model year 2000 and newer passenger vehicles. Data from NASS-CDS were used to describe characteristics of occupants in the front and rear rows and to determine the risk of serious injury (AIS 3+) for restrained rear row occupants by occupant age, vehicle model year, and impact direction. Using a combined data set containing data on fatalities from FARS and estimates of the total population of occupants in crashes from NASS-CDS, logistic regression modeling was used to compute the relative risk (RR) of death for restrained occupants in the rear vs. front passenger seat by occupant age, impact direction, and vehicle model year.

RESULTS

Among all vehicle occupants in tow-away crashes during 2007-2012, 12.3% were in the rear row where the overall risk of serious injury was 1.3%. Among restrained rear row occupants, the risk of serious injury varied by occupant age, with older adults at the highest risk of serious injury (2.9%); by impact direction, with rollover crashes associated with the highest risk (1.5%); and by vehicle model year, with model year 2007 and newer vehicles having the lowest risk of serious injury (0.3%). Relative risk of death was lower for restrained children up to age 8 in the rear compared with passengers in the right front seat (RR=0.27, 95% CI 0.12-0.58 for 0-3 years, RR=0.55, 95% CI 0.30-0.98 for 4-8 years) but was higher for restrained 9-12-year-old children (RR=1.83, 95% CI 1.18-2.84). There was no evidence for a difference in risk of death in the rear vs. front seat for occupants ages 13-54, but there was some evidence for an increased relative risk of death for adults age 55 and older in the rear vs. passengers in the right front seat (RR=1.41, 95% CI 0.94-2.13), though we could not exclude the possibility of no difference. After controlling for occupant age and gender, the relative risk of death for restrained rear row occupants was significantly higher than that of front seat occupants in model year 2007 and newer vehicles and significantly higher in rear and right side impact crashes.

CONCLUSIONS

Results of this study extend prior research on the relative safety of the rear seat compared with the front by examining a more contemporary fleet of vehicles. The rear row is primarily occupied by children and adolescents, but the variable relative risk of death in the rear compared with the front seat for occupants of different age groups highlights the challenges in providing optimal protection to a wide range of rear seat occupants. Findings of an elevated risk of death for rear row occupants, as compared with front row passengers, in the newest model year vehicles provides further evidence that rear seat safety is not keeping pace with advances in the front seat.

Burden of road traffic injuries: Disability-adjusted life years in relation to hospitalization and the maximum abbreviated injury scale

BACKGROUND

The consequences of non-fatal road traffic injuries (RTI) are increasingly adopted by policy makers as an indicator of traffic safety. However, it is not agreed upon which level of severity should be used as cut-off point for assessing road safety performance. Internationally, within road safety, injury severity is assessed by means of the maximum abbreviated injury scale (MAIS). The choice for a severity cut-off point highly influences the measured disease burden of RTI. This paper assesses the burden of RTI in terms of disability adjusted life years (DALYs) by hospitalization status and MAIS cut-off point in the Netherlands.

METHODS

Hospital discharge register (HDR) and emergency department (ED) data for RTI in the Netherlands were selected for the years 2007-2009, as well as mortality data. The incidence, years lived with disability (YLD), years of life lost (YLL) owing to premature death, and DALYs were calculated. YLD for admitted patients was subdivided by MAIS severity levels.

RESULTS

RTI resulted in 48,500 YLD and 27,900 YLL respectively, amounting to 76,400 DALYs per year in the Netherlands. The largest proportion of DALYs is related to fatalities (37%), followed by admitted MAIS 2 injuries (25%), ED treated injuries (16%) and admitted MAIS 3+ injuries (18%). Admitted MAIS 1 injuries only account for a small fraction of DALYs (4%). In the Netherlands, the diseases burden of RTI is highest among cyclists with 39% of total DALYs. One half of all bicycle related DALYs are attributable to admitted MAIS 2+ injuries, but ED treated injuries also account for a large proportion of DALYs in this group (28%). Car occupants are responsible for 26% of all DALYs, primarily caused by fatalities (66%), followed by admitted MAIS 2+ injuries (25%). ED treated injuries only account for 5% of DALYs in this group.

CONCLUSIONS

When using admitted MAIS 3+ or admitted MAIS 2+ as severity cut-off point, 54% and 80% of all DALYs are captured respectively. Assessing the influence of different severity cut-off points by MAIS on the proportion and number of DALYs captured gives valuable information for guiding choices on the definition of serious RTI.

Regional pressure and temperature variations across the injured human brain: comparisons between paired intraparenchymal and ventricular measurements

INTRODUCTION

Intraparenchymal, multimodality sensors are commonly used in the management of patients with severe traumatic brain injury (TBI). The 'gold standard', based on accuracy, reliability and cost for intracranial pressure (ICP) monitoring is within the cerebral ventricle (external strain gauge). There are no standards yet for intracerebral temperature monitoring and little is known of temperature differences between brain tissue and ventricle. The aim of the study therefore was to determine pressure and temperature differences at intraparenchymal and ventricular sites during five days of continuous neuromonitoring.

METHODS

Patients with severe TBI requiring emergency surgery.

INCLUSION CRITERIA

patients who required ICP monitoring were eligible for recruitment. Two intracerebral probe types were used: a) intraventricular, dual parameter sensor (measuring pressure, temperature) with inbuilt catheter for CSF drainage: b) multiparameter intraparenchymal sensor measuring pressure, temperature and oxygen partial pressure. All sensors were inserted during surgery and under aseptic conditions.

RESULTS

Seventeen patients, 12 undergoing neurosurgery (decompressive craniectomy n = 8, craniotomy n = 4) aged 21-78 years were studied. Agreement of measures for 9540 brain tissue-ventricular temperature 'pairs' and 10,291 brain tissue-ventricular pressure 'pairs' were determined using mixed model to compare mean temperature and pressure for longitudinal data. There was no significant overall difference for mean temperature (p = 0.92) or mean pressure readings (p = 0.379) between tissue and ventricular sites. With 95.8 % of paired temperature readings within 2SD (-0.4 to 0.4 °C) differences in temperature between brain tissue and ventricle were clinically insignificant. For pressure, 93.5 % of readings pairs fell within the 2SD range (-9.4756 to 7.8112 mmHg). However, for individual patients, agreement for mean tissue-ventricular pressure differences was poor on occasions.

CONCLUSIONS

There is good overall agreement between paired temperature measurements obtained from deep white matter and brain ventricle in patients with and without early neurosurgery. For paired ICP measurements, 93.5 % of readings were within 2SD of mean difference. Whilst the majority of paired readings were comparable (within 10 mmHg) clinically relevant tissue-ventricular dissociations were noted. Further work is required to unravel the events responsible for short intervals of pressure dissociation before tissue pressure readings can be definitively accepted as a reliable surrogate for ventricular pressure.

Evaluation of developmental metrics for utilization in a pediatric advanced automatic crash notification algorithm

OBJECTIVE

Appropriate treatment at designated trauma centers (TCs) improves outcomes among injured children after motor vehicle crashes (MVCs). Advanced Automatic Crash Notification (AACN) has shown promise in improving triage to appropriate TCs. Pediatric-specific AACN algorithms have not yet been created. To create such an algorithm, it will be necessary to include some metric of development (age, height, or weight) as a covariate in the injury risk algorithm. This study sought to determine which marker of development should serve as a covariate in such an algorithm and to quantify injury risk at different levels of this metric.

METHODS

A retrospective review of occupants age < 19 years within the MVC data set NASS-CDS 2000-2011 was performed. R(2) values of logistic regression models using age, height, or weight to predict 18 key injury types were compared to determine which metric should be used as a covariate in a pediatric AACN algorithm. Clinical judgment, literature review, and chi-square analysis were used to create groupings of the chosen metric that would discriminate injury patterns. Adjusted odds of particular injury types at the different levels of this metric were calculated from logistic regression while controlling for gender, vehicle velocity change (delta V), belted status (optimal, suboptimal, or unrestrained), and crash mode (rollover, rear, frontal, near-side, or far-side).

RESULTS

NASS-CDS analysis produced 11,541 occupants age < 19 years with nonmissing data. Age, height, and weight were correlated with one another and with injury patterns. Age demonstrated the best predictive power in injury patterns and was categorized into bins of 0-4 years, 5-9 years, 10-14 years, and 15-18 years. Age was a significant predictor of all 18 injury types evaluated even when controlling for all other confounders and when controlling for age- and gender-specific body mass index (BMI) classifications. Adjusted odds of key injury types with respect to these age categorizations revealed that younger children were at increased odds of sustaining Abbreviated Injury Scale (AIS) 2+ and 3+ head injuries and AIS 3+ spinal injuries, whereas older children were at increased odds of sustaining thoracic fractures, AIS 3+ abdominal injuries, and AIS 2+ upper and lower extremity injuries.

CONCLUSIONS

The injury patterns observed across developmental metrics in this study mirror those previously described among children with blunt trauma. This study identifies age as the metric best suited for use in a pediatric AACN algorithm and utilizes 12 years of data to provide quantifiable risks of particular injuries at different levels of this metric. This risk quantification will have important predictive purposes in a pediatric-specific AACN algorithm.

Outcomes of decompressive craniectomy in patients after traumatic brain injury

OBJECTIVE

Traumatic brain injury (TBI) can result in cerebral oedema and vascular changes resulting in an increase in intracranial pressure (ICP), which can lead to further secondary damage. Decompressive craniectomy (DC) is a surgical option in the management of ICP. We aimed to investigate outcomes of DC after TBI.

DESIGN

We performed a retrospective audit of 57 adult patients (aged > 15 years) who underwent DC after TBI, at the Royal Melbourne Hospital from 1 January 2005 to 30 June 2011. Our functional outcome measure was the Extended Glasgow Outcome Scale (GOSE).

RESULTS

Patients had a median age of 30 years (range, 17- 73 years). The hospital mortality rate was 47% (27 patients). A higher postoperative median ICP was the most significant predictor of hospital mortality (OR, 1.1; 95% CI, 1-1.3). There was a mean decrease of 7.7mmHg in ICP between the mean preoperative and postoperative ICP values (95% CI, - 10.5 to - 5.0mmHg). There was a mean decrease of 3.5mmHg in the mean cerebral perfusion pressure (CPP) from preoperative to postoperative CPP values (95% CI, - 6.2 to - 0.8mmHg). At the 6-month follow-up, a poor outcome (GOSE score, 1-4) was seen in 39 patients (68%), while a good outcome (GOSE score, 5- 8) was noted in 15 patients (26%). A high APACHE II score on admission was the most significant predictor of a worse GOSE score at 6 months (OR, 1.3; 95% CI, 1.1-1.5). Analysis of the APACHE II and IMPACT scores as models for predicting mortality at 6 months showed an area under the curve (AUC) of 0.792 and 0.805, respectively, and for predicting poor outcome at 6 months, showed an AUC of 0.862 and 0.883, respectively.

CONCLUSION

DC decreased ICP postoperatively. The IMPACT and APACHE II scores are good models for prediction of death and poor outcome at 6 months.

Predicting patients that require care at a trauma center: analysis of injuries and other factors

INTRODUCTION

The detection of occult or unpredictable injuries in motor vehicle crashes (MVCs) is crucial in correctly triaging patients and thus reducing fatalities. The purpose of the study was to develop a metric that indicates the likelihood that an injury sustained in a MVC would require management at a Level I/II trauma centre (TC) versus a non-trauma centre (non-TC).

METHODS

Transfer Scores (TSs) were computed for 240 injuries that comprise the top 95% most frequently occurring injuries in the National Automotive Sampling System-Crashworthiness Data System (NASS-CDS) with an Abbreviated Injury Scale (AIS) severity of 2 or greater. A TS for each injury was computed using the proportions of patients involved in a MVC from the National Inpatient Sample (NIS) that were transferred to a TC or managed at a non-TC. Similarly, a TSMAIS that excludes patients with higher severity co-injuries was calculated using the proportion of patients with a maximum AIS (MAIS) equal to the AIS severity of a given injury.

RESULTS

The results indicated for injuries of a given AIS severity, body region, and injury type, there were large variations in the TSMAIS. Overall results demonstrated higher TSMAIS values when injuries were internal, haemorrhagic, intracranial or of moderate severity (AIS 3-5). Specifically, injuries to the head possessed a TSMAIS that ranged from 0.000 to 0.889, with head injuries of AIS 3-5 severities being the most likely to be transferred.

DISCUSSION AND CONCLUSIONS

The analysis indicated that the TSMAIS is not solely correlated with AIS severity and therefore it captures other important aspects of injury such as predictability and trauma system capabilities. The TS and TSMAIS can be useful in advanced automatic crash notification (AACN) research for the detection of highly unpredictable injuries in MVCs that require direct transport to a TC.

Concussion, Diffuse Axonal Injury, and AIS4+ Head Injury in Motor Vehicle Crashes

PURPOSE

This is a descriptive study of the annual incidence of brain injuries in motor vehicle crashes by type, seat belt use, and crash severity (delta V) using national accident data. The risk for concussion, diffuse axonal injury (DAI), and severe head injury was determined.

METHODS

1994-2011 NASS-CDS was analyzed to estimate the number of brain injuries annually in nonejected adults involved in motor vehicle crashes. Crashes were grouped by front, side, rear, and rollover, and the effect of belt use was investigated. Light vehicles were included with model year 1994+. Head injuries were identified as concussion, DAI, severe head injury (Abbreviated Injury Scale [AIS] 4+), and skull fracture. The annual incidence, risk, and rate for different types of head injury were estimated with standard errors.

RESULTS

Motor vehicle crashes involved 33,191 ± 7,815 occupants with concussion, 5,665 ± 996 with AIS 4+ head injuries, 986 ± 446 with DAI, and 3,300 ± 531 with skull fracture annually. The risk was 1.64 ± 0.39% for concussion, 0.28 ± 0.05% for severe head injury (AIS 4+), 0.05 ± 0.02% for DAI, and 0.16 ± 0.03% for skull fracture in tow-away crashes. The risk for severe head injury (AIS 4+) was highest in rollovers (0.74 ± 0.16%) and lowest in rear impacts (0.17 ± 0.05%). Head injury risk depended on seat belt use, crash type, and crash severity (delta V). Seat belt use lowered the risk for AIS 4+ head injury by 74.8% and skull fracture by 73.2%.

CONCLUSIONS

Concussions occur in about one out of 61 occupants in tow-away crashes. The risk was highest in rollover crashes (4.73 ± 1.09%) and it was reduced 69.2% by seat belt use. Severe brain injuries occurred less often and the risk was also reduced by seat belt use.

Expanding pedestrian injury risk to the body region level: how to model passive safety systems in pedestrian injury risk functions

OBJECTIVE

Assessment of the effectiveness of advanced driver assistance systems (ADAS) plays a crucial role in accident research. A common way to evaluate the effectiveness of new systems is to determine the potentials for injury severity reduction. Because injury risk functions describe the probability of an injury of a given severity conditional on a technical accident severity (closing speed, delta V, barrier equivalent speed, etc.), they are predestined for such evaluations.

METHODS

Recent work has stated an approach on how to model the pedestrian injury risk in pedestrian-to-passenger car accidents as a family of functions. This approach gave explicit and easily interpretable formulae for the injury risk conditional on the closing speed of the car. These results are extended to injury risk functions for pedestrian body regions. Starting with a double-checked German In-depth Accident Study (GIDAS) pedestrian-to-car accident data set (N = 444) and a functional-anatomical definition of the body regions, investigations on the influence of specific body regions on the overall injury severity will be presented. As the measure of injury severity, the ISSx, a rescaled version of the well-known Injury Severity Score (ISS), was used. Though traditional ISS is computed by summation of the squares of the 3 most severe injured body regions, ISSx is computed by the summation of the exponentials of the Abbreviated Injury Scale (AIS) severities of the 3 most severely injured body regions. The exponentials used are scaled to fit the ISS range of values between 0 and 75.

RESULTS

Three body regions (head/face/neck, thorax, hip/legs) clearly dominated abdominal and upper extremity injuries; that is, the latter 2 body regions had no influence at all on the overall injury risk over the range of technical accident severities. Thus, the ISSx is well described by use of the injury codes from the same body regions for any pedestrian injury severity. As a mathematical consequence, the ISSx becomes explicitly decomposable into the 3 body regions and so are the risk functions as body region-specific risk functions. The risk functions for each body region are stated explicitly for different injury severity levels and compared to the real-world accident data.

CONCLUSIONS

The body region-specific risk functions can then be used to model the effect of improved passive safety systems. These modified body region-specific injury risk functions are aggregated to a new pedestrian injury risk function. Passive safety systems can therefore be modeled in injury risk functions for the first time. A short example on how the results can be used for assessing the effectiveness of new driver assistance systems concludes the article.

NASS-CDS analysis of high retention seat performance in rear impacts

PURPOSE

A recent study used the Fatality Analysis Reporting System (FARS) to determine the safety performance of high retention seats in fatal rear impacts. The odds of fatal injury were reduced 46.3% (95% confidence interval [CI], 39.3-52.4, z = 9.982, P <.0001) with high retention seats. This study extends the earlier one by establishing an exposure group of nonfatal occupants in towaway crashes using NASS-CDS.

METHODS

The 2001-2008 NASS-CDS was analyzed for rear impacts of 1992 to 2008 model year GM vehicles with high retention or baseline seats using the same search strategy as in FARS. Injuries were analyzed by severity (Maximum Abbreviated Injury Scale [MAIS]). The number of fatalities from FARS and number of nonfatal occupants from NASS-CDS were used to determine the risk for fatal injury in towaway crashes with 5-7 o'clock principal direction of force (PDOF). The odds ratio for fatal injury and the change in fatality risk were determined with ±95% confidence intervals, z-statistics, and significance levels. Injury risks were also determined using NASS-CDS.

RESULTS

Based on 2001-2008 FARS and NASS-CDS, the fatality risk was 0.21% in high retention seats and 0.39% in baseline seats in 5-7 o'clock towaway crashes. The odds for fatality were 46.8% (95% CI, 39.8-53.0, z = 10.001, P <.0001) lower with high retention seats. There was a higher trend for lower serious-to-critical injury in high retention seats than baseline seats in NASS-CDS. Six electronic cases were available in NASS-CDS with fatal injury in high retention seats. Only one involved the seat performance as a factor in the fatality, a 72-year-old belted female in a 14 mph rear delta V impact who experienced fractures of the thoracic spine. Her upper body likely wrapped around the upright seatback.

CONCLUSIONS

High retention seats significantly reduced the odds for fatal injury in towaway crashes with 5-7 o'clock PDOF. There was a trend for lower serious-to-critical injury risks, but more data are needed to determine significant differences.

Mortality Risk in Pediatric Motor Vehicle Crash Occupants: Accounting for Developmental Stage and Challenging Abbreviated Injury Scale Metrics

OBJECTIVE

Survival risk ratios (SRRs) and their probabilistic counterpart, mortality risk ratios (MRRs), have been shown to be at odds with Abbreviated Injury Scale (AIS) severity scores for particular injuries in adults. SRRs have been validated for pediatrics but have not been studied within the context of pediatric age stratifications. We hypothesized that children with similar motor vehicle crash (MVC) injuries may have different mortality risks (MR) based upon developmental stage and that these MRs may not correlate with AIS severity.

METHODS

The NASS-CDS 2000-2011 was used to define the top 95% most common AIS 2+ injuries among MVC occupants in 4 age groups: 0-4, 5-9, 10-14, and 15-18 years. Next, the National Trauma Databank 2002-2011 was used to calculate the MR (proportion of those dying with an injury to those sustaining the injury) and the co-injury-adjusted MR (MRMAIS) for each injury within 6 age groups: 0-4, 5-9, 10-14, 15-18, 0-18, and 19+ years. MR differences were evaluated between age groups aggregately, between age groups based upon anatomic injury patterns and between age groups on an individual injury level using nonparametric Wilcoxon tests and chi-square or Fisher's exact tests as appropriate. Correlation between AIS and MR within each age group was also evaluated.

RESULTS

MR and MRMAIS distributions of the most common AIS 2+ injuries were right skewed. Aggregate MR of these most common injuries varied between the age groups, with 5- to 9-year-old and 10- to 14-year-old children having the lowest MRs and 0- to 4-year-old and 15- to 18-year-old children and adults having the highest MRs (all P <.05). Head and thoracic injuries imparted the greatest mortality risk in all age groups with median MRMAIS ranging from 0 to 6% and 0 to 4.5%, respectively. Injuries to particular body regions also varied with respect to MR based upon age. For example, thoracic injuries in adults had significantly higher MRMAIS than such injuries among 5- to 9-year-olds and 10- to 14-year-olds (P =.04; P <.01). Furthermore, though AIS was positively correlated with MR within each age group, less correlation was seen for children than for adults. Large MR variations were seen within each AIS grade, with some lower AIS severity injuries demonstrating greater MRs than higher AIS severity injuries. As an example, MRMAIS in 0- to 18-year-olds was 0.4% for an AIS 3 radius fracture versus 1.4% for an AIS 2 vault fracture.

CONCLUSIONS

Trauma severity metrics are important for outcome prediction models and can be used in pediatric triage algorithms and other injury research. Trauma severity may vary for similar injuries based upon developmental stage, and this difference should be reflected in severity metrics. The MR-based data-driven determination of injury severity in pediatric occupants of different age cohorts provides a supplement or an alternative to AIS severity classification for pediatric occupants in MVCs.

Real-World Rib Fracture Patterns in Frontal Crashes in Different Restraint Conditions

OBJECTIVE

The purpose of this study was to use the detailed medical injury information in the Crash Injury Research and Engineering Network (CIREN) to evaluate patterns of rib fractures in real-world crash occupants in both belted and unbelted restraint conditions. Fracture patterns binned into rib regional levels were examined to determine normative trends associated with belt use and other possible contributing factors.

METHODS

Front row adult occupants with Abbreviated Injury Scale (AIS) 3+ rib fractures, in frontal crashes with a deployed frontal airbag, were selected from the CIREN database. The circumferential location of each rib fracture (with respect to the sternum) was documented using a previously published method (Ritchie et al. 2006) and digital computed tomography scans. Fracture patterns for different crash and occupant parameters (restraint use, involved physical component, occupant kinematics, crash principal direction of force, and occupant age) were compared qualitatively and quantitatively.

RESULTS

There were 158 belted and 44 unbelted occupants included in this study. For belted occupants, fractures were mainly located near the path of the shoulder belt, with the majority of fractures occurring on the inboard (with respect to the vehicle) side of the thorax. For unbelted occupants, fractures were approximately symmetric and distributed across both sides of the thorax. There were negligible differences in fracture patterns between occupants with frontal (0°) and near side (330° to 350° for drivers; 10° to 30° for passengers) crash principal directions of force but substantial differences between groups when occupant kinematics (and contacts within the vehicle) were considered. Age also affected fracture pattern, with fractures tending to occur more anteriorly in older occupants and more laterally in younger occupants (both belted and unbelted).

CONCLUSIONS

Results of this study confirmed with real-world data that rib fracture patterns in unbelted occupants were more distributed and symmetric across the thorax compared to belted occupants in crashes with a deployed frontal airbag. Other factors, such as occupant kinematics and occupant age, also produced differing patterns of fractures. Normative data on rib fracture patterns in real-world occupants can contribute to understanding injury mechanisms and the role of different causation factors, which can ultimately help prevent fractures and improve vehicle safety.

Association Between NCAP Ratings and Real-World Rear Seat Occupant Risk of Injury

OBJECTIVE

Several studies have evaluated the correlation between U.S. or Euro New Car Assessment Program (NCAP) ratings and injury risk to front seat occupants, in particular driver injuries. Conversely, little is known about whether NCAP 5-star ratings predict real-world risk of injury to restrained rear seat occupants. The NHTSA has identified rear seat occupant protection as a specific area under consideration for improvements to its NCAP. In order to inform NHTSA's efforts, we examined how NCAP's current 5-star rating system predicts risk of moderate or greater injury among restrained rear seat occupants in real-world crashes.

METHODS

We identified crash-involved vehicles, model year 2004-2013, in NASS-CDS (2003-2012) with known make and model and nonmissing occupant information. We manually matched these vehicles to their NCAP star ratings using data on make, model, model year, body type, and other identifying information. The resultant linked NASS-CDS and NCAP database was analyzed to examine associations between vehicle ratings and rear seat occupant injury risk; risk to front seat occupants was also estimated for comparison. Data were limited to restrained occupants and occupant injuries were defined as any injury with a maximum Abbreviated Injury Scale (AIS) score of 2 or greater.

RESULTS

We linked 95% of vehicles in NASS-CDS to a specific vehicle in NCAP. The 18,218 vehicles represented an estimated 6 million vehicles with over 9 million occupants. Rear seat passengers accounted for 12.4% of restrained occupants. The risk of injury in all crashes for restrained rear seat occupants was lower in vehicles with a 5-star driver rating in frontal impact tests (1.4%) than with 4 or fewer stars (2.6%, P =.015); results were similar for the frontal impact passenger rating (1.3% vs. 2.4%, P =.024). Conversely, side impact driver and passenger crash tests were not associated with rear seat occupant injury risk (driver test: 1.7% for 5-star vs. 1.8% for 1-4 stars; passenger test: 1.6% for 5 stars vs 1.8% for 1-4 stars).

CONCLUSIONS

Current frontal impact test procedures provide some degree of discrimination in real-world rear seat injury risk among vehicles with 5 compared to fewer than 5 stars. However, there is no evidence that vehicles with a 5-star side impact passenger rating, which is the only crash test procedure to include an anthropomorphic test dummy (ATD) in the rear, demonstrate lower risks of injury in the rear than vehicles with fewer than 5 stars. These results support prioritizing modifications to the NCAP program that specifically evaluate rear seat injury risk to restrained occupants of all ages.

Can a Boxer Engine Reduce Leg Injuries Among Motorcyclists? Analysis of Injury Distributions in Crashes Involving Different Motorcycles Fitted with Antilock Brakes (ABS)

OBJECTIVES

Several studies have shown that motorcycle antilock braking systems (ABS) reduce crashes and injuries. However, it has been suggested that the improved stability provided by ABS would make upright crashes more frequent, thus changing the injury distributions among motorcyclists and increasing the risk of leg injuries. The overall motorcycle design can vary across different categories and manufacturers. For instance, some motorcycles are equipped with boxer-twin engines; that is, with protruding cylinder heads. A previous study based on a limited material has suggested that these could provide some leg protection; therefore, the aim of this research was to analyze injury distributions in crashes involving ABS-equipped motorcycles with boxer-twin engines compared to similar ABS-equipped motorcycles with other engine configurations.

METHODS

Swedish hospital and police records from 2003-2014 were used. Crashes involving ABS-equipped motorcycles with boxer-twin engines (n = 55) were compared with similar ABS-equipped motorcycles with other engines configurations (n = 127). The distributions of Abbreviated Injury Scale (AIS) 1+ and AIS 2+ were compared. Each subject's injury scores were also converted to the risk for permanent medical impairment (RPMI), which shows the risk of different levels of permanent medical impairment given the severity and location and of injuries. To compare injury severity, the mean RPMI 1+ and RPMI 10+ were analyzed for each body region and in overall for each group of motorcyclists.

RESULTS

It was found that AIS 1+, AIS 2+, and PMI 1+ leg injuries were reduced by approximately 50% among riders with boxer engines. These results were statistically significant. The number of injuries to the upper body did not increase; the mean RPMI to the head and upper body were similar across the 2 groups, suggesting that the severity of injuries did not increase either. Indications were found suggesting that the overall mean RPMI 1+ was lower among riders with boxer engines, although this result was not statistically significant. The mean values of the overall RPMI 10+ were similar.

CONCLUSIONS

Boxer-twin engines were not originally developed to improve motorcycle crashworthiness. However, the present article indicates that these engines can reduce leg injuries among riders of motorcycles fitted with ABS. Though it is recommended that future research should look deeper into this particular aspect, the present findings suggest that the concept of integrated leg protection is indeed feasible and that further engineering efforts in this area are likely to yield significant savings in health losses among motorcyclists.

Evaluation of Vehicle-Based Crash Severity Metrics

OBJECTIVE

Vehicle change in velocity (delta-v) is a widely used crash severity metric used to estimate occupant injury risk. Despite its widespread use, delta-v has several limitations. Of most concern, delta-v is a vehicle-based metric which does not consider the crash pulse or the performance of occupant restraints, e.g. seatbelts and airbags. Such criticisms have prompted the search for alternative impact severity metrics based upon vehicle kinematics. The purpose of this study was to assess the ability of the occupant impact velocity (OIV), acceleration severity index (ASI), vehicle pulse index (VPI), and maximum delta-v (delta-v) to predict serious injury in real world crashes.

METHODS

The study was based on the analysis of event data recorders (EDRs) downloaded from the National Automotive Sampling System / Crashworthiness Data System (NASS-CDS) 2000-2013 cases. All vehicles in the sample were GM passenger cars and light trucks involved in a frontal collision. Rollover crashes were excluded. Vehicles were restricted to single-event crashes that caused an airbag deployment. All EDR data were checked for a successful, completed recording of the event and that the crash pulse was complete. The maximum abbreviated injury scale (MAIS) was used to describe occupant injury outcome. Drivers were categorized into either non-seriously injured group (MAIS2-) or seriously injured group (MAIS3+), based on the severity of any injuries to the thorax, abdomen, and spine. ASI and OIV were calculated according to the Manual for Assessing Safety Hardware. VPI was calculated according to ISO/TR 12353-3, with vehicle-specific parameters determined from U.S. New Car Assessment Program crash tests. Using binary logistic regression, the cumulative probability of injury risk was determined for each metric and assessed for statistical significance, goodness-of-fit, and prediction accuracy.

RESULTS

The dataset included 102,744 vehicles. A Wald chi-square test showed each vehicle-based crash severity metric estimate to be a significant predictor in the model (p < 0.05). For the belted drivers, both OIV and VPI were significantly better predictors of serious injury than delta-v (p < 0.05). For the unbelted drivers, there was no statistically significant difference between delta-v, OIV, VPI, and ASI.

CONCLUSIONS

The broad findings of this study suggest it is feasible to improve injury prediction if we consider adding restraint performance to classic measures, e.g. delta-v. Applications, such as advanced automatic crash notification, should consider the use of different metrics for belted versus unbelted occupants.