Occupational Injury Surveillance Using the Washington State Trauma Registry

Differential underestimation of work-related reinjury risk for older workers: Challenges to producing accurate rate estimates

BACKGROUND

Older workers are increasingly represented in the U.S. workforce, but frequently work part-timeor intermittently, hindering accurate injury rate estimates. To reduce the impact of reporting barriers on rate comparisons, we focused on reinjury (both injury recurrence and new injury) among workers with a workers' compensation claim, assessing: (1) reinjury risk for workers age 65+ versus <65; (2) importance of work-time at-risk measurement for rate estimates and comparisons; and (3) age distribution of potential risk factors.

METHODS

Washington State workers' compensation claims for a retrospective cohort of workers with work-related permanent impairments were linked to state wage files. Reinjury rates were calculated for the cohort (N = 11,184) and a survey sample (N = 582), using both calendar time and full-time equivalent (FTE)-adjusted time. Risk differentials were assessed using rate ratios and adjusted survival models.

RESULTS

The rate ratio for workers age 65+ (vs. <65) was 0.45 (p < 0.001) using calendar time, but 0.70 (p = 0.07) using FTE-adjusted time. Survey-based rates were 35.7 per 100 worker-years for workers age 65+, versus 14.8 for <65. Workers age 65+ (vs. <65) were more likely to work <100% FTE, but were similar regarding job strain, their ability to handle physical job demands, and their comfort reporting unsafe conditions or injuries.

CONCLUSIONS

Accounting for work-time at risk substantially improves age-based reinjury comparisons. Although the marked elevation in self-reported reinjury risk for older workers might be a small-sample artifact (n = 34), workers age 65+ are likely at higher risk than previously appreciated. Ongoing workforce trends demand increased attention to injury surveillance and prevention for older workers.

Workers' compensation claims for traumatic brain injuries among private employers-Ohio, 2001-2011

BACKGROUND

The purpose of this analysis was to identify and prioritize high-risk industry groups for traumatic brain injury (TBI) prevention efforts.

METHODS

Workers with TBI from 2001 to 2011 were identified from the Ohio Bureau of Workers' Compensation data. To prioritize industry groups by claim type (lost-time (≥8 days away from work) and total claims) and injury event categories, we used a prevention index (PI) that averaged TBI counts and rate ranks (PI = (count rank + rate rank)/2). TBI rates per 10 000 estimated full-time equivalent (FTE = 2000 h/y) workers were calculated.

RESULTS

From 2001 to 2011, 12 891 TBIs were identified among private employers, resulting in a rate of 5.1 TBIs per 10 000 FTEs. Of these, 40% (n = 5171) were lost-time TBIs, at a rate of 2.0 per 10 000 FTEs. Spectator Sports had the highest lost-time TBI rate (13.5 per 10 000 FTEs), whereas General Freight Trucking had the greatest number of lost-time TBIs (n = 293). Based on PIs, General Freight Trucking ranked first for lost-time TBIs for all injury events combined. Several industry groups within Construction, General and Specialized Freight Trucking, Services to Building and Dwellings, Employment Services, and Restaurants and Other Eating Places ranked high across multiple injury event categories for lost-time TBIs.

CONCLUSIONS

The high-ranking industry groups identified from our study can be used to effectively direct occupational TBI prevention efforts.

Frequency of Operative Anesthesia Care After Traumatic Injury

BACKGROUND

Virtually all anesthesiologists care for patients who sustain traumatic injuries; however, the frequency with which operative anesthesia care is provided to this specific patient population is unclear. We sought to better understand the degree to which anesthesia providers participate in operative trauma care and how this differs by trauma center designation (levels I-V), using data from a comprehensive, regional database-the Washington State Trauma Registry (WSTR). We also sought to specifically assess operative anesthesia care frequency vis a vis the American College of Surgeons guidelines for continuous anesthesiology coverage for Level II trauma center accreditation.

METHODS

We conducted a retrospective analysis measuring the frequency of operative anesthesia care among patients enrolled in the WSTR. Univariate comparisons were made between trauma patients who had surgery during their admission and those who did not (medical management only). In addition, clinical factors associated with surgical intervention were measured. We also measured the average times from hospital admission to surgery and compared these times across trauma centers, grouped level I, II, and III-V.

RESULTS

From 2004 to 2014, there were approximately 176,000 encounters meeting WSTR inclusion criteria. Approximately 60% of these trauma encounters included exposure to operative anesthesia during the admission. Among all surgical procedures during the trauma admission, approximately 33% occurred within a level I trauma center, 23% occurred within a level II trauma center, and 44% occurred in a trauma center with a III, IV, or V designation. The predominant procedure category during a trauma admission was orthopedic. The presence of hypotension on admission (P < .01), increasing injury severity score (P < .01) and higher emergency department Glasgow Coma Score (P < .01) were all associated with surgical intervention during the trauma hospitalization, after adjustment for potential confounders. In level I trauma centers, for general surgical procedures, the median time to surgery was 2.5 hours; in level II trauma centers, the median time was 1.7 hours.

CONCLUSIONS

This study highlights the frequent role anesthesiologists play in caring for patients who sustain traumatic injuries, in trauma centers levels I-V. In level II trauma centers, in-house anesthesiology coverage might have benefit for those patients requiring surgery within 1 hour, whereas the former American College of Surgeons requirement of 30-minute response time for out-of-hospital anesthesiology coverage is likely sufficient to provide satisfactory care to patients requiring surgery within 3 hours. Whether the increased cost of such in-house anesthesiology coverage at level II trauma centers is justified by its clinical benefit remains an unanswered question.

The epidemiology of work-related injury admissions to hospitals in the Midland region of New Zealand

OBJECTIVE

To describe the epidemiological characteristics of patients with work-related injuries (WRI) admitted to hospitals in New Zealand's Midland Trauma System (MTS) during a four year period.

METHODS

A retrospective review was conducted of trauma registry records for adults (≥15years) admitted to four hospitals in the MTS as a result of WRI between 1 January 2012 and 31 December 2015. We describe the patterns of injury incidence by demographic characteristics, employment industry, mechanism of injury, body regions injured, injury severity score (ISS), month, day and time of injury, duration of hospital stay, domicile District Health Board (DHB), and discharge destination.

RESULTS

The 2169 WRI trauma admissions, corresponded to an annualised rate of 205.8 per 100,000 workers or 234.3 per 100,000 full time employment employees (FTE). Injury rates were highest among males (238.0 per 100,000 workers) and those aged 15-24 years (227.1 per 100,000 workers), and lowest among Asians (83 per 100,000 workers). The highest injury rates occurred among the 'agriculture/forestry/fishing', 'manufacturing', and 'transport/postal/warehousing' industries. 'Contact with machinery' was the most common mechanism of injury, and the 'extremities or pelvic girdle' the most common body region injured. The in-hospital case fatality rate was <0.5%.

CONCLUSION

The predominance of WRI in the 'agriculture/forestry/fishing' industries in the Midland region is consistent with national estimates. The high rate of injuries amongst males, young adults, and Māori requires further exploration.

State Trauma Registries as a Resource for Occupational Injury Surveillance and Research: Lessons From Washington State, 1998-2009

OBJECTIVES

Work-related traumatic injury is a leading cause of death and disability among US workers. Occupational injury surveillance is necessary for effective prevention planning and assessing progress toward Healthy People 2020 objectives. Our objectives were to (1) describe the Washington State Trauma Registry (WTR) as a resource for occupational injury surveillance and research, (2) compare the WTR with 2 population-based data sources more widely used for these purposes, and (3) compare the number of injuries ascertained by the WTR with other data sources.

METHODS

We linked WTR records to hospital discharge records in the Comprehensive Hospital Abstract Reporting System for 2009 and to workers' compensation claims from the Washington State Department of Labor and Industries for 1998 to 2008. We assessed the 3 data sources for overlap, concordance, and case ascertainment.

RESULTS

Of 9185 work-related injuries in the WTR, 3380 (37%) did not link to workers' compensation claims. Use of payer information in hospital discharge records along with the WTR work-relatedness field identified 20% more linked injuries as work related (n = 720) than did use of payer information alone (n = 602). The WTR identified substantial numbers of work-related injuries that were not identified through workers' compensation or hospital discharge records.

CONCLUSIONS

Workers' compensation and hospital discharge databases are important but incomplete data sources for work-related injuries; many work-related injuries are not billed to, reported to, or covered by workers' compensation. Trauma registries are well positioned to capture severe work-related injuries and should be included in comprehensive injury surveillance efforts.

Classifying, measuring and improving the quality of data in trauma registries: A review of the literature

INTRODUCTION

Globally, injury is a major cause of death and disability. Improvements in trauma care have been driven by trauma registries. The capacity of a trauma registry to inform improvements in the quality of trauma care is dependent upon the quality of data. The literature on data quality in disease registries is inconsistent and ambiguous; methods used for classifying, measuring, and improving data quality are not standardised. The aim of this study was to review the literature to determine the methods used to classify, measure and improve data quality in trauma registries.

METHODS

A scoping review of the literature was performed. Databases were searched using the term "trauma registry" and its synonyms, combined with multiple terms denoting data quality. There was no restriction on year. Full-length manuscripts were included if the classification, measurement or improvement of data quality in one or more trauma registries was a study objective. Data were abstracted regarding registry demographics, study design, data quality classification, and the reported methods used to measure and improve the pre-defined data quality dimensions of accuracy, completeness and capture.

RESULTS

Sixty-nine publications met the inclusion criteria. Four publications classified data quality. The most frequently described methods for measuring data accuracy (n=47) were checks against other datasets (n=18) and checks of injury coding (n=17). The most frequently described methods for measuring data completeness (n=47) were the percentage of included cases, for a given variable or list of variables, for which there was an observation in the registry (n=29). The most frequently described methods for measuring data capture (n=37) were the percentage of cases in a linked reference dataset that were also captured in the primary dataset being evaluated (n=24). Most publications dealing with the measurement of a dimension of data quality did not specify the methods used; most publications dealing with the improvement of data quality did not specify the dimension being targeted.

CONCLUSION

The classification, measurement and improvement of data quality in trauma registries is inconsistent. To maintain confidence in the usefulness of trauma registries, the metrics and reporting of data quality need to be standardised.

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.

Developing Surveillance Methodology for Agricultural and Logging Injury in New Hampshire Using Electronic Administrative Data Sets

OBJECTIVE

Agriculture and logging rank among industries with the highest rates of occupational fatality and injury. Establishing a nonfatal injury surveillance system is a top priority in the National Occupational Research Agenda. Sources of data such as patient care reports (PCRs) and hospitalization data have recently transitioned to electronic databases.

METHODS

Using narrative and location codes from PCRs, along with International Classification of Diseases, 9th Revision, external cause of injury codes (E-codes) in hospital data, researchers are designing a surveillance system to track farm and logging injury.

RESULTS

A total of 357 true agricultural or logging cases were identified.

CONCLUSIONS

These data indicate that it is possible to identify agricultural and logging injury events in PCR and hospital data. Multiple data sources increase catchment; nevertheless, limitations in methods of identification of agricultural and logging injury contribute to the likely undercount of injury events.

Linkage and concordance of Trauma Registry and hospital discharge records: lessons for occupational injury surveillance and research

OBJECTIVE

Occupational injury researchers typically use payer to identify work-related injuries in hospital discharge records. Many trauma registries contain a work-related field, independent of payer. Linked trauma registry and hospital discharge records were used to assess data field concordance and to assess the validity of using payer or external cause of injury (E-codes) to identify work-related injuries.

METHODS

Washington State Trauma Registry records were linked to hospital discharges (year 2009).

RESULTS

There was substantial agreement between Washington State Trauma Registry and hospital discharge records for workers' compensation as primary payer. E-code based methods of identifying occupational injuries had high specificity (more than 99%) but low sensitivity (less than 14%). Payer was 76% sensitive and 98% specific.

CONCLUSIONS

This study found substantial agreement for data fields key to occupational injury surveillance and research. Nevertheless, many work-related injuries could not be identified using hospital discharge records.

The economic and logistical burden of care for severe work-related injuries in a level 1 tertiary care trauma referral center

BACKGROUND

Work-related injuries (WRIs) represent a significant economic and logistical burden to healthcare systems.

METHODS

All patients with severe WRIs (Injury Severity Score [ISS] ≥ 12) (1995 to 2013) were compared with patients with non-WRIs using standard methodology (P < .05).

RESULTS

A total of 1,270 (8.5%) trauma admissions were for severe WRIs (mean age = 45 years, male:female ratio = 2.8:1, mean ISS = 22.7). Compared with patients with non-WRIs, WRI patients were younger, male, and had fewer comorbidities. Despite equivalent ISS, WRIs had a longer intensive care unit length of stay, length of mechanical ventilation, and number of surgical/operative procedures. Fewer patients with WRIs died in hospital and more were discharged home without support services. The acute care economic burden of WRIs was higher (because of intensive care unit and operating theatre, and physician compensation) (all analyses, P < .05).

CONCLUSION

Patients with WRIs were younger, less comorbid, male, and had significantly higher utilization of acute care resources despite a similar ISS.

Disparities in occupational injury hospitalization rates in five states (2003-2009)

BACKGROUND

Achievement of health equity and elimination of disparities are overarching goals of Healthy People 2020, yet there is a paucity of population-based data regarding race/ethnicity-based disparities in occupational injuries.

METHODS

Hospital discharge data for five states (Arizona, California, Florida, New Jersey, and New York) were obtained from the Healthcare Cost & Utilization Project (HCUP) for 2003-2009. Age-adjusted rates and trends for work-related injury hospitalizations were calculated using negative binomial regression (reference category: non-Latino white).

RESULTS

Latinos were significantly more likely to have a work-related traumatic injury hospitalization. The disparity for Latinos was greatest for machinery-related hospitalizations. Latinos were also more likely to have a fall-related hospitalization. African-Americans were more likely to have an occupational assault-related hospitalization, but less likely to have a fall-related hospitalization.

CONCLUSIONS

We found evidence of substantial multistate disparities in occupational injury-related hospitalizations. Enhanced surveillance and further research are needed to identify and address underlying causes.

Epidemiology of work-related traumatic brain injury: a systematic review

OBJECTIVE

This systematic review aimed to describe the burden and risk factors of work-related traumatic brain injury (wrTBI) and evaluate methodological quality of existing literature on wrTBI.

METHODS

A search of electronic databases (MEDLINE, EMBASE, PsycINFO, and CINAHL) was conducted to identify articles published between 1980 and 2013 using a combination of terms for work, TBI, and epidemiology, without geographical limitations.

RESULTS

Ninety-eight studies were included in this review, of which 24 specifically focused on wrTBI. In general, male workers, those in the youngest and oldest age groups, and those working in the primary (e.g., agriculture, forestry, mining) or construction industries were more likely to sustain wrTBI, with falls being the most common mechanism of injury.

CONCLUSIONS

This review identified workers at highest risk of wrTBI, with implications for prevention efforts. Future research of better methodological quality is needed to provide a more complete picture of the epidemiology of wrTBI.

Occupational injury trends derived from trauma registry and hospital discharge records: lessons for surveillance and research

OBJECTIVE

The suitability of the Washington State Trauma Registry (WTR) for occupational injury surveillance was assessed via comparing estimated rates and trends with those derived from state hospital discharge data.

METHODS

Descriptive methods and negative binomial regression were used to model occupational injury trends (1998 to 2009).

RESULTS

Nonlinear trends based on WTR data closely tracked those based on hospital discharge data, beginning about 2002. Rate estimates differed somewhat by data source and were most similar when a severity threshold was applied. Conclusions regarding temporal trends in work-related injury rates were the same using either data source.

CONCLUSIONS

This study found substantial similarity between occupational injury trends estimated using either WTR or hospital discharge data. We conclude that a mature state trauma registry with mandatory reporting requirements can be used for surveillance of severe work-related traumatic injuries.

Using injury severity to improve occupational injury trend estimates

BACKGROUND

Hospitalization-based estimates of trends in injury incidence are also affected by trends in health care practices and payer coverage that may differentially impact minor injuries. This study assessed whether implementing a severity threshold would improve occupational injury surveillance.

METHODS

Hospital discharge data from four states and a national survey were used to identify traumatic injuries (1998-2009). Negative binomial regression was used to model injury trends with/without severity restriction, and to test trend divergence by severity.

RESULTS

Trend estimates were generally biased downward in the absence of severity restriction, more so for occupational than non-occupational injuries. Restriction to severe injuries provided a markedly different overall picture of trends.

CONCLUSIONS

Severity restriction may improve occupational injury trend estimates by reducing temporal biases such as increasingly restrictive hospital admission practices, constricting workers' compensation coverage, and decreasing identification/reporting of minor work-related injuries. Injury severity measures should be developed for occupational injury surveillance systems.

Workplace-related traumatic injuries: insights from a rapidly developing Middle Eastern country

Traumatic workplace-related injuries (WRIs) carry a substantial negative impact on the public health worldwide. We aimed to study the incidence and outcomes of WRIs in Qatar. We conducted occupational injury surveillance for all WRI patients between 2010 and 2012. A total of 5152 patients were admitted to the level 1 trauma unit in Qatar, of which 1496 (29%) sustained WRI with a mean age of 34.3 ± 10.3. Fall from height (FFH) (51%) followed by being struck by heavy objects (FHO) (18%) and motor vehicle crashes (MVC) (17%) was the commonest mechanism of injury (MOI). WRI patients were mainly laborers involved in industrial work (43%), transportation (18%), installation/repair (12%), carpentry (9%), and housekeeping (3%). Use of protective device was not observed in 64% of cases. The mean ISS was 11.7 ± 8.9, median ICU stay was 3 days (1–64), and total hospital stay was 6 days (1–192). The overall case fatality was 3.7%. Although the incidence of WRI in Qatar is quite substantial, its mortality rate is relatively low in comparison to other countries of similar socioeconomic status. Prolonged hospital stay and treatment exert a significant socioeconomic burden on the nation's and families' resources. Focused and efficient injury prevention strategies are mandatory to prevent future WRI.

Case identification of work-related traumatic brain injury using the occupational injury and illness classification system

OBJECTIVES

Traumatic brain injury (TBI) is one of the most common, costly, and disabling occupational injuries. Objectives included determining whether work-related TBI could be reliably identified using the Occupational Injury and Illness Classification System (OIICS) and describing challenges in developing an OIICS-based TBI case definition.

METHODS

Washington State trauma registry reports and workers' compensation claims were linked (1998 to 2008). Trauma registry diagnoses were used as the gold standard for six OIICS-based TBI case definitions.

RESULTS

The OIICS-based case definitions were highly specific but had low sensitivity, capturing less than a third of fatal and nonfatal TBI.

CONCLUSION

The use of OIICS versus International Classification of Diseases-Ninth Revision-Clinical Modification codes underestimated TBI and changed the attributable cause distribution, with potential implications for prevention efforts. Surveillance methods that can more fully and accurately capture the impact of work-related TBI across the United States are needed.

Predicting work-related disability and medical cost outcomes: a comparison of injury severity scoring methods

INTRODUCTION

Acute work-related trauma is a leading cause of death and disability among U.S. workers. Occupational health services researchers have described the pressing need to identify valid injury severity measures for purposes such as case-mix adjustment and the construction of appropriate comparison groups in programme evaluation, intervention, quality improvement, and outcome studies. The objective of this study was to compare the performance of several injury severity scores and scoring methods in the context of predicting work-related disability and medical cost outcomes.

METHODS

Washington State Trauma Registry (WTR) records for injuries treated from 1998 to 2008 were linked with workers' compensation claims. Several Abbreviated Injury Scale (AIS)-based injury severity measures (ISS, New ISS, maximum AIS) were estimated directly from ICD-9-CM codes using two software packages: (1) ICDMAP-90, and (2) Stata's user-written ICDPIC programme (ICDPIC). ICDMAP-90 and ICDPIC scores were compared with existing WTR scores using the Akaike Information Criterion, amount of variance explained, and estimated effects on outcomes. Competing risks survival analysis was used to evaluate work disability outcomes. Adjusted total medical costs were modelled using linear regression.

RESULTS

The linked sample contained 6052 work-related injury events. There was substantial agreement between WTR scores and those estimated by ICDMAP-90 (kappa=0.73), and between WTR scores and those estimated by ICDPIC (kappa=0.68). Work disability and medical costs increased monotonically with injury severity, and injury severity was a significant predictor of work disability and medical cost outcomes in all models. WTR and ICDMAP-90 scores performed better with regard to predicting outcomes than did ICDPIC scores, but effect estimates were similar. Of the three severity measures, maxAIS was usually weakest, except when predicting total permanent disability.

CONCLUSIONS

Injury severity was significantly associated with work disability and medical cost outcomes for work-related injuries. Injury severity can be estimated using either ICDMAP-90 or ICDPIC when ICD-9-CM codes are available. We observed little practical difference between severity measures or scoring methods. This study demonstrated that using existing software to estimate injury severity may be useful to enhance occupational injury surveillance and research.

Who pays for work-related traumatic injuries? Payer distribution in washington state by ethnicity, injury severity, and year (1998-2008)

BACKGROUND

Acute work-related trauma is a leading cause of death and disability for U.S. workers but it is difficult to obtain information about injured workers not covered by workers' compensation (WC). This study aimed to: (1) describe trends in expected payer and linkage to WC claims, (2) compare characteristics of injured workers who did and did not have a linked WC claim, and (3) describe variation in expected payer and linkage to WC claims by ethnicity and injury severity.

METHODS

Data for injuries occurring from 1998 through 2008 were obtained from the Washington State Trauma Registry and linked to WC claims.

RESULTS

We found that 27% of work-related traumatic injuries did not have WC listed as a payer, while 37% did not link to a WC claim. Among those with WC listed as a payer, the odds of having a linked WC claim were 57% lower for workers with other non-WC insurance compared with the otherwise uninsured. Latinos were more likely to have a linked WC claim compared with non-Latinos, but there was no significant difference after partially controlling for WC-covered employment and other insurance.

CONCLUSIONS

This study demonstrated the importance of considering differential access to other insurance coverage and adaptation by health care settings to financial pressures when assessing trends in occupational injury incidence and reporting, especially when using WC as a proxy for work-relatedness. The addition of occupation, industry, and work status to trauma registries and hospital discharge databases would improve surveillance, research, policy and prevention efforts.

The burden of traumatic brain injury among adolescent and young adult workers in Washington State

OBJECTIVE

This study describes injury characteristics and costs of work-related traumatic brain injury (WRTBI) among 16-24 year olds in Washington State between 1998 and 2008.

METHODS

WRTBIs were identified in the Washington Trauma Registry (WTR) and linked to workers' compensation (WC) claims data. Medical and time-loss compensation costs were compared between workers with isolated TBI and TBI with other trauma.

RESULTS

Of 273 WRTBI cases identified, most (61.5%) were TBI with other trauma. One-third of WRTBI did not link to a WC claim. Medical costs averaged $88,307 (median $16,426) for isolated TBI cases, compared to $73,669 (median $41,167) for TBI with other trauma.

CONCLUSIONS

Results highlight the financial impact of WRTBI among young workers. Multiple data sources provided a more comprehensive picture than a single data source alone. This linked-data approach holds great potential for future traumatic occupational injury research.

IMPACT ON INDUSTRY

TBI among young workers not only involves long-term health and psychological impacts, but is costly as well.

Predicting work-related disability and medical cost outcomes: estimating injury severity scores from workers' compensation data

PURPOSE

Acute work-related trauma is a leading cause of death and disability among US workers. The research objectives were to assess: (1) the feasibility of estimating Abbreviated Injury Scale-based injury severity scores (ISS) from ICD-9-CM codes available in workers' compensation (WC) medical billing data, (2) whether ISS predicts work-related disability and medical cost outcomes, (3) whether ISS adds value over other injury severity proxies, and (4) whether the utility of ISS differs for an all-injury sample compared with three specific injury samples (amputations, extremity fractures, traumatic brain injury).

METHODS

ISS was estimated from ICD-9-CM codes using Stata's user-written -icdpic- program for 208,522 compensable nonfatal WC claims for workers injured in Washington State from 1998 to 2008. The Akaike Information Criterion and R(2) were used to compare severity measures. Competing risks survival analysis was used to evaluate work disability outcomes. Adjusted total medical costs were modeled using linear regression.

RESULTS

Work disability and medical costs increased monotonically with injury severity. For a subset of 4,301 claims linked to the Washington State Trauma Registry (WTR), there was moderate agreement between WC-based ISS and WTR-based ISS. Including ISS together with an early hospitalization indicator resulted in the most informative models; however, early hospitalization is a more downstream measure.

CONCLUSIONS

ISS was significantly associated with work disability and medical cost outcomes for work-related injuries. Injury severity should be considered as a potential confounder for occupational injury intervention, program evaluation, or outcome studies, and can be estimated using existing software when ICD-9-CM codes are available.