Racial differences in the validity of self-reported drug use among men who have sex with men in Atlanta, GA.

BACKGROUND: Men who have sex with men (MSM), particularly young black MSM, are disproportionately affected in the United States' HIV epidemic. Drug use may contribute to these disparities, yet previous studies have failed to provide evidence of elevated use among black MSM, relying exclusively on self-reported usage. This study uses biological assays to validate self-reports of drug use and explore the potential for misclassification to distort findings on racial patterns of use in this population.
METHODS: From an Atlanta-based cohort study of 454 black and 349 white MSM from 2010 to 2012, participants' self-reported drug use was compared to urine drug screening findings. The sensitivity of self-report was calculated as the proportion reporting recent usage among those who screened positive. Multivariable regression models were constructed to examine racial patterns in self-report, urine-detection, and self-report sensitivity of marijuana and cocaine usage, adjusted for socio-demographic factors.
RESULTS: In analyses that adjusted for age, education, income, sexual orientation, and history of arrest, black MSM were less likely to report recent use of marijuana (P<0.001) and cocaine (P=0.02), but equally likely to screen positive for either drug. This discrepancy between self-reported and urine-detected drug use was explained by significantly lower sensitivity of self-report for black participants (P<0.001 for marijuana, P<0.05 for cocaine).
CONCLUSIONS: The contribution of individual drug-related risk behaviors to the HIV disparities between black and white MSM should be revisited with methods that validate self-reports of illegal drug use.