Prevalence and reporting of occupational illness by company size: population trends and regulatory implications.

BACKGROUND Reports of occupational disease using the Bureau of Labor Statistics (BLS)/OSHA survey have shown increasing rates with larger establishment size. The literature is divided on whether this pattern is an artifact of under-reporting in smaller businesses or is the result of differences in underlying risk factors. METHODS A population-based survey [the Connecticut Upper-Extremity Surveillance Project (CUSP)] assessing prevalence of likely work related musculoskeletal disorders (MSD) in CT, coded by establishment size, is compared to CT MSD incidence rates based on the BLS/OSHA survey. RESULTS When analyses were controlled for age, gender, physical risks, and occupation, there was a marginally significant association between business size and the rate of MSD [odds ratio (OR) = 0.91, CI 0.82-1.01], but in the opposite direction of the BLS/OSHA rates, with larger businesses having somewhat lower rates of MSD. Reported risk factors varied in a similar direction, though with mid-sized companies having the highest physical risks. CONCLUSIONS The increased rates of occupational illness in larger businesses reported in the BLS/OSHA survey does not appear to be due to actual incidence or distribution of risk factors, but appears more likely to be due to under-reporting in smaller businesses. Estimates based on the assumption that the ORs based on size are actually similar to the CUSP population survey results suggest that MSD incidence is approximately 3.6-times the reported rates.