The law and incomplete database information as confounders in epidemiologic research on occupational injuries and illnesses

BACKGROUND: Capture-recapture studies report undercounting of work injuries/illnesses with days away from work (DAFW) in the Bureau of Labor Statistics annual Survey of Occupational Injuries and Illnesses (BLS SOII) by 25-68% depending on the state and undercounting by various state workers' compensation (WC) systems of eligible claims by 5-35%. METHODS: Statutory/regulatory criteria defining eligible cases are used to adjust counts in the 1998-2001 Minnesota's WC system and the BLS SOII to permit comparison and to evaluate the recent studies. Missing information in the employer database used in the capture-recapture studies is tabulated. An attempt is made to harmonize results with two additional databases counting work injuries. RESULTS: Counts in the BLS SOII moderately undercount by 10-16% the number of WC cases. We believe that matching in capture-recapture studies is adversely affected by misperceptions regarding the application of statutory/regulatory eligibility criteria and by missing data. The result is that the reported undercounts in both the BLS SOII and several state WC databases are overstated in the capture-recapture studies. Although three of four databases can be approximately harmonized, the fourth cannot. CONCLUSIONS: More precisely targeted information is needed before decisions regarding redesign of the BLS survey are made or before legislative or administrative changes in the WC are contemplated.