Race and sex disparities in Worker Compensation coverage for work-related emergency department visits

Because payment by Worker Compensation (WC) for treatment is considered reliable evidence of work-relatedness, WC claims are often used as proxy measures for calculating occupational injury rates. However, not all workers are covered by WC, including many temporary, contract, undocumented and self-employed workers. These workers represent an increasing proportion of the workforce. To the extent injury patterns among workers not covered by WC differ systematically from those among covered workers, the generalization of WC-based surveillance and research findings is invalid and can lead to underestimation of rates and mask disparities. To assess differences in patient characteristics of work-related emergency department (ED) visits not paid versus paid by WC, we analyzed data from the combined ED files of the 2003 – 2006 National Hospital Ambulatory Medical Care Surveys (NHAMCS-ED), which determines work-relatedness independently of expected payer. The proportion of non-WC visits, as a share of all work-related ED visits, increased each year from 32.1% in 2003 to 44.9% in 2006, a statistically significant trend. The overall proportion of non-WC visits was 39.6% (95% C.I. 36.5 – 42.8%). This proportion was significantly greater among Blacks (53.0%, p < 0.01). After stratification by sex, this association remained significant for women (60.5%, p < 0.01) but not for men (47.8%, p = 0.06), suggesting effect modification. These results suggest WC claims represent a diminishing share of acute occupational injuries, and that black women are disproportionally represented among non-WC, work-related visits. WC-based rates of occupational injury for this group should be interpreted cautiously.