The effectiveness of preemployment drug screening in the prediction of employment outcome.

Studies of adverse employment outcomes associated with positive preemployment drug screens have tracked employees for only about 1 year. Changes in drug use after hire may invalidate the predictions of employment outcome in later years which are essential for cost-benefit analyses. This blinded, prospective cohort study tracks absence, industrial accidents, occupational injuries, discipline, and turnover in 2537 screened employees through an average of 2 years. Marijuana-positive urines predicted increased turnover, accidents, injuries, discipline, and absence, but these risks appeared lower in the second year than the first. Cocaine-positive urines predicted increased turnover, accidents, injuries, discipline, and absence at levels not consistently different than the first year. Cost-benefit analyses of drug screening project employment risks throughout employees' careers. This study raises the possibility that elevated risks may decrease after the first year.