Prevalence of recent illicit substance use and reporting bias among MSM and other urban males.

This paper explores whether elevated rates of self-reported substance use among MSM compared to other males may be an artifact of reporting bias. Past month prevalence rates of marijuana, cocaine, heroin, methamphetamine, Ecstasy, and Ketamine use were compared between a sample of men who have sex with men (MSM), and a general household sample of men, all residing in Chicago. We compared rates of self-reported use, and corrected rates based on the results of drug testing (urine and oral fluid tests). While MSM over 30 years old were significantly more likely than other men in this age group to report past month use of cocaine, test-corrected rates of use were equivalent. On the other hand, test-corrected estimates confirmed elevated rates of Ketamine and Ecstasy use in the MSM sample. Differential disclosure of substance use between MSM and other males may in some cases lead to distorted conclusions about differences in substance use between these groups. The use of biological testing in epidemiological studies of substance use can reduce the uncertainty of such comparisons.