Surveillance of Acute Work-Related Injury Hospitalizations in California Using the Workers' Compensation Information System

BACKGROUND:  There is a recognized need for improved surveillance of work-related injuries in the US. In California, electronic reporting of First Reports Of Injury (FROIs) to the state’s Workers’ Compensation Information System (WCIS) has been required since 2000, and medical billing data associated with claims has been required since 2006. We used this data reporting infrastructure to quantify work-related acute injury hospitalizations in California and to identify risk factors associated with these cases.

METHODS:  We extracted all claims submitted to WCIS  through 12/31/2013 meeting our case definition for acute injury hospitalization: hospital admission date ≤1 day of the injury date;  medical bill with Facility Code of 11 (Hospital/Inpatient), 17 (Hospital/Subacute Inpatient), or 21 (Skilled Nursing/Inpatient); and medical bill with a Revenue Billed Code for room and board or treatment in an intensive or coronary care unit. We reviewed medical records of a random sample of cases to validate our case definition.

RESULTS:  A total of 17,162 cases met our definition for acute hospitalization from 2000-2013. We limited our analysis to cases occurring from 1/1/2010 through 12/31/2013 (n=6,842) to ensure consistency across years in the matching of FROI data with medical bills. During this period, the age-adjusted case rate per 100,000 workers declined from 12.4 to 8.8. Sex-adjusted rates were approximately 5 times higher among men than women, with the 55-64 year male age group experiencing the highest injury rate (range: 16.1-25.5 cases/100,000) each year. The median length of hospitalization was 2 (interquartile range: 1,5) days, and the median dollar amount paid per medical bill was $10,725. Fall or slip was the most frequent cause of injury; laborer, carpenter, and roofer were the most common occupations cited with these cases. 

CONCLUSIONS:  Acute injury hospitalizations represent a significant burden of work-related morbidity in California, accounting for approximately 5 times the number of annual occupational fatalities. Workers’ compensation claims data can be used to ascertain hospitalization for acute injuries among workers and to identify key demographic and occupational characteristics. Consideration should be given to the routine analysis of acute work-related injury hospitalization data for evaluation of OSHA-mandated employer reporting, compliance inspections, and public health intervention.