Unreported workers' compensation claims to the BLS Survey of Occupational Injuries and Illnesses: Establishment factors.

Background: Studies suggest employers underreport injuries to the Bureau of Labor Statistics Survey of Occupational Injuries and Illnesses (SOII); less is known about reporting differences by establishment characteristics.

Methods: We linked SOII data to Washington State workers' compensation claims data, using unemployment insurance data to improve linking accuracy. We used multivariable regression models to estimate incidence ratios (IR) of unreported workers' compensation claims for establishment characteristics.

Results: An estimated 70% of workers' compensation claims were reported in SOII. Claims among state and local government establishments were most likely to be reported. Compared to large manufacturing establishments, unreported claims were most common among small educational services establishments (IR = 2.47, 95%CI: 1.52-4.01) and large construction establishments (IR = 2.05, 95%CI: 1.77-2.37).

Conclusions: Underreporting of workers' compensation claims to SOII varies by establishment characteristics, obscuring true differences in work injury incidence. Findings may differ from previous research due to differences in study methods.