Illness severity adjustment for outcomes analysis: Validation of the ICISS methodology in all 821,455 patients hospitalized in North Carolina in 1996

Trauma scores and trauma outcome measures

Objective measurement and quantification of injury severity are necessary for triage, performance evaluation and research. In order to evaluate interventions, outcomes must also be compared. While this can be done using hospital stay or mortality, these will fail to detect subtle differences. Impact of injury on health can be quantified using a variety of scoring systems. Trauma scoring and outcome measurement have grown increasingly complex in recent years and are likely to become more so in the future.

Establishing an injury indicator for severe paediatric injury

BACKGROUND

Routinely gathered injury data, such as hospitalisations, may be subject to variation from sources other than injury incidence. There is a need for an indicator that defines severe injury, which may be less vulnerable to fluctuations due to changes in care policies. The purpose of this study was to identify International Classification of Diseases-10 codes associated with severe paediatric injuries and to specify and validate a severe paediatric injury indicator.

METHODS

Two data sets that included the ISS and the survival risk ratio were used to produce a list of diagnoses to define severe paediatric injury. The list was sent to trauma surgeons who classified each code as severe enough or not severe enough to require care in a trauma centre. The indicator was fully specified, then validated by using a different data set to validate the codes in a real-world situation.

RESULTS

Sixty diagnoses were identified as representing severe paediatric injury. Following specification, the indicator was applied to an existing comprehensive data set of paediatric injuries. The decline in hospitalisation of paediatric injuries was significantly steeper for severe than non-severe injuries, suggesting that factors related to the decline in this trauma subset are unlikely to be related to changes in access or other components of trauma care delivery.

CONCLUSIONS

This indicator can be used for the evaluation of trends in severe paediatric trauma and will help identify populations at risk. This research may inform policies and procedures for referrals of severe childhood injury to appropriate levels of care.

Intramedullary lesion expansion on magnetic resonance imaging in patients with motor complete cervical spinal cord injury

OBJECT

The authors performed a study to determine if lesion expansion occurs in humans during the early hours after spinal cord injury (SCI), as has been established in rodent models of SCI, and to identify factors that might predict lesion expansion.

METHODS

The authors studied 42 patients with acute cervical SCI and admission American Spinal Injury Association Impairment Scale Grades A (35 patients) and B (7 patients) in whom 2 consecutive MRI scans were obtained 3-134 hours after trauma. They recorded demographic data, clinical information, Injury Severity Score (ISS), admission MRI-documented spinal canal and cord characteristics, and management strategies.

RESULTS

The characteristics of the cohort were as follows: male/female ratio 37:5; mean age, 34.6 years; and cause of injury, motor vehicle collision, falls, and sport injuries in 40 of 42 cases. The first MRI study was performed 6.8 ±2.7 hours (mean ± SD) after injury, and the second was performed 54.5 ± 32.3 hours after injury. The rostrocaudal intramedullary length of the lesion on the first MRI scan was 59.2 ± 16.1 mm, whereas its length on the second was 88.5 ± 31.9 mm. The principal factors associated with lesion length on the first MRI study were the time between injury and imaging (p = 0.05) and the time to decompression (p = 0.03). The lesion's rate of rostrocaudal intramedullary expansion in the interval between the first and second MRI was 0.9 ± 0.8 mm/hour. The principal factors associated with the rate of expansion were the maximum spinal cord compression (p = 0.03) and the mechanism of injury (p = 0.05).

CONCLUSIONS

Spinal cord injury in humans is characterized by lesion expansion during the hours following trauma. Lesion expansion has a positive relationship with spinal cord compression and may be mitigated by early surgical decompression. Lesion expansion may be a novel surrogate measure by which to assess therapeutic effects in surgical or drug trials.

Are all trauma centers created equally? A statewide analysis

OBJECTIVES

Prior work has shown differences in mortality at different levels of trauma centers (TCs). There are limited data comparing mortality of equivalently verified TCs. This study sought to assess the potential differences in mortality as well as discharge destination (discharge to home vs. to a rehabilitation center or skilled nursing facility) across Level I TCs in the state of Ohio.

METHODS

This was a retrospective, multicenter, statewide analysis of a state trauma registry of American College of Surgeons (ACS)-verified Level I TCs from 2003 to 2006. All adult (>15 years) patients transferred from the scene to one of the 10 Level I TCs throughout the state were included (n = 16,849). Multivariable logistic regression models were developed to assess for differences in mortality, keeping each TC as a fixed-effect term and adjusting for patient demographics, injury severity, mechanism of injury, and emergency medical services and emergency department procedures. Outcomes included in-hospital mortality and discharge destination (home vs. rehabilitation center or skilled nursing facility). Adjusted odds ratios (ORs) for each TC were also calculated.

RESULTS

Considerable variability existed in unadjusted mortality between the centers, from 3.8% (95% confidence interval [CI] = 3.7% to 3.9%) to 24.2% (95% CI = 24.1% to 24.3%), despite similar patient characteristics and injury severity. Adjusted mortality had similar variability as well, ranging from an OR of 0.93 (95% CI = 0.47 to 1.84) to an OR of 6.02 (95% CI= 3.70 to 9.79). Similar results were seen with the secondary outcomes (discharge destination).

CONCLUSIONS

There is considerable variability in the mortality of injured patients at Level I TCs in the state of Ohio. The patient differences or care processes responsible for this variation should be explored.

Epidemiology of Fatal Trauma in Italy in 2002 Using Population-Based Registries

BACKGROUND

Population-based registries have been proposed for epidemiologic studies and quality assessment in trauma care because they consider the entire population of a given geographic area.

PATIENTS AND METHODS

Trauma mortality in pre-hospital and in-hospital settings and death time from injury have been calculated for Italy during 2002 by cross-analyzing two national databases: the death certificates register (DCD) and the hospital discharge register (HDR). All diagnosis codes from 800.0 to 939.9 and from 950.0 to 959.9 in both the DCD and the HDR, with the exclusion of femur fractures (820.0 and 821.9) if older than 65, have been included.

RESULTS

The total number of people who died during 2002 as a consequence of trauma in Italy was 15,456; of these, 43.5% were older than age 64, and 35.9% belonged to the 15-44 age group. The overall incidence rate of trauma death was 27.23 per 100,000 inhabitants/ year, with a relative risk to men vs. women of 2.3. An analysis of the time distribution of the trauma deaths showed that 46.8% were pre-hospital mortalities, 18% of the deaths occurred within 48 h after hospital admission (acute mortality), 11.2% of the deaths occurred between three and seven days after admission (early mortality), and 24.0% of the patients died more than seven days after admission (late mortality). Patients who died before they arrived at hospital were younger and the proportion of men was higher than for the deaths that occurred after hospital arrival.

CONCLUSION

The use of population-based registries proved to be effective in our study because it allowed us to use currently available data to obtain information useful for trauma system planning and design.

Canadian benchmarks in trauma

BACKGROUND

Benchmarks are used in trauma care for program evaluation, quality improvement, and research. National outcome benchmarks relevant to the Canadian trauma population need to be defined for evaluation of trauma care in Canada. The purpose of this study was to derive survival probabilities associated with trauma diagnoses using International Classification of Diseases, Ninth Revision (ICD-9) codes.

METHODS

All patients admitted to an acute care hospital with nonpenetrating trauma and submitted to the National Trauma Registry of Canada between 1994 through 2000 inclusively were included in analyses. Both inclusive and exclusive survival risk ratios (SRRs) were calculated for groups of ICD-9 injury codes between 800 to 959.

RESULTS

For the study period, there were 1,003,905 and 803,776 eligible trauma patients used to calculate inclusive SRRs and exclusive SRRs, respectively. Survival probabilities for injuries are given according to ICD-9 codes.

CONCLUSION

This is the first study to define national survival benchmarks for the Canadian trauma population. These results can be used to assess survival of patients using the ICISS [(ICD-9) based Injury Severity Score (ISS)] methodology. With regular updates, these data can further be developed for continual trauma outcome assessment, quality improvement, and research into trauma care in Canada.

The national pediatric trauma registry: a legacy of commitment to control of childhood injury

The National Pediatric Trauma Registry represents almost 15 years of effective collaboration among hospitals committed to improving care for the injured child. Its design of providing a "physiologic snapshot" of the injured child on presentation has supported numerous studies that have helped define the epidemiology of childhood injury and refine principles of management. Global analysis of the 103,434 records included in this database suggest that mortality is significantly higher in the very young, that vehicular injury remains a major pediatric public health challenge, and that shock is just as devastating in the child as the adult. Based on this foundation of collaborative commitment, future versions of a pediatric trauma database must harness the emerging internet technology that combines information accrual with human thought, and must extend this effort to include all the children of our world.

A multicenter evaluation of whether gender dimorphism affects survival after trauma

BACKGROUND

The frequency of women who have sustained severe injuries has increased over the past 30 years. The purpose of this study was to evaluate whether severely injured women have a survival advantage over men. To address this issue, we undertook a multicenter evaluation of the effects of gender dimorphism on survival in trauma patients.

METHODS

Patient information was collected from the databases of three level I trauma centers. We included all consecutive patients who were admitted to these centers over a 4-year period. We evaluated the effects of age, gender, mechanism of injury, pattern of injury, Abbreviated Injury Score (AIS), and Injury Severity Score (ISS) on survival.

RESULTS

A total of 20,261 patients were admitted to the three trauma centers. Women who were younger than 50 years of age (mortality rate 5%) experienced a survival advantage over men (mortality rate 7%) of equal age (odds ratio 1.27, P <0.002). This advantage was most notably found in the more severely injured (ISS >25) group (mortality rate 28% in women versus 33% in men). This difference was not attributable to mechanism of injury, severity of injury, or pattern of injury.

CONCLUSIONS

Severely injured women younger than 50 years of age have a survival advantage when compared with men of equal age and injury severity. Young men have a 27% greater chance of dying than women after trauma. We conclude that gender dimorphism affects the survival of patients after trauma.

An artificial neural network as a model for prediction of survival in trauma patients: validation for a regional trauma area

BACKGROUND

To develop and validate an artificial neural network (ANN) for predicting survival of trauma patients based on standard prehospital variables, emergency room admission variables, and Injury Severity Score (ISS) using data derived from a regional area trauma system, and to compare this model with known trauma scoring systems.

PATIENT POPULATION

The study was composed of 10,609 patients admitted to 24 hospitals comprising a seven-county suburban/rural trauma region adjacent to a major metropolitan area. The data was generated as part of the New York State trauma registry. Study period was from January 1993 through December 1996 (1993-1994: 5,168 patients; 1995: 2,768 patients; 1996: 2,673 patients).

METHODS

A standard feed-forward back-propagation neural network was developed using Glasgow Coma Scale, systolic blood pressure, heart rate, respiratory rate, temperature, hematocrit, age, sex, intubation status, ICD-9-CM Injury E-code, and ISS as input variables. The network had a single layer of hidden nodes. Initial network development of the model was performed on the 1993-1994 data. Subsequent models were generated using the 1993, 1994, and 1995 data. The model was tested first on the 1995 and then on the 1996 data. The ANN model was tested against Trauma and Injury Severity Score (TRISS) and ISS using the receiver operator characteristic (ROC) area under the curve [ROC-A(z)], Lemeshow-Hosmer C-statistic, and calibration curves.

RESULTS

The ANN showed good clustering of the data, with good separation of nonsurvivors and survivors. The ROCA(z) was 0.912 for the ANN, 0.895 for TRISS, and 0.766 for ISS. The ANN exceeded TRISS with respect to calibration (Lemeshow-Hosmer C-statistic: 7.4 for ANN; 17.1 for TRISS). The prediction of survivors was good for both models. The ANN exceeded TRISS in nonsurvivor prediction.

CONCLUSION

An ANN developed for trauma patients using prehospital, emergency room admission data, and ISS gave good prediction of survival. It was accurate and had excellent calibration. This study expands our previous results developed at a single Level I trauma center and shows that an ANN model for predicting trauma deaths can be applied across hospitals with good results

Elderly injury: a profile of trauma experience in the Sunshine (Retirement) State

OBJECTIVE

By using mandatory discharge data from a state agency, the records of 116,687 patients hospitalized for treatment of injury were evaluated to develop an epidemiologic and demographic profile of this population and to compare outcomes of patients treated in state-designated trauma centers (TC) with those treated in nontrauma centers (NTC).

METHODS

Injury severity was calculated by using the International Classification Injury Severity Score methodology to compute individual diagnosis survival risk ratios from 698,187 reported diagnoses, and then by using these survival risk ratios to determine probability of survival for every patient. The population was then categorized by age, injury type, treatment facility designation, injury severity as indicated by probability of survival, and discharge disposition. Incidence of potentially preventable death was compared between TC and NTC, as was the effect on outcome of noninjury comorbidity.

RESULTS

The average age of this population was 58 +/- 26 years with significant skew toward the elderly in NTC (mean age, 62 +/- 26 years). The most commonly encountered injuries likewise reflected the elderly nature of this population. Although 71.3% received care in NTC, the majority of severely injured were treated in TC. Potentially preventable mortality (>0.5) was significantly lower in TC. The effect of noninjury comorbidity on outcome was better managed by TC, both in terms of decreased mortality and in proportion of patients discharged home.

CONCLUSION

These data demonstrate the unique characteristics of injury victims treated in the state of Florida and indicate that the developing trauma system is demonstrating productivity in terms of avoidance of preventable death, efficient management of noninjury comorbid problems, and more complete recovery as indicated by proportion of patients discharged to home.