Assessing drug use prevalence in the workplace: a comparison of self-report methods and urinalysis

A random sample of 800 employees of a steel manufacturing company were randomly assigned to one of four self-report methods of assessing illicit drug use: 1) Individual interview in the workplace, 2) group-administered questionnaire in the workplace, 3) telephone interview, and 4) individual interview off the worksite. All 621 subjects participating in the research were also tested by urinalysis. Rates of drug use self-report were highest in the workplace interview condition and lowest in the overall group questionnaire condition. Although the overall prevalence rates produced by self-reports and urinalysis were similar, there was little concordance between urinalysis positives and self-report positives. The results indicated that self-reports and urinalysis are complementary methods of drug use assessment, and are best used in combination.