What’s the Agreement between Self-Reported and Biochemical Verification of Drug Use? A Look at Permanent Supportive Housing Residents in Ft. Worth

People who are chronically homeless are nearly seven times as likely to use illicit drugs, compared to the general population. We evaluated the validity of self-reported drug use in a sample of previously homeless people housed in permanent supportive housing programs in Ft. Worth. We used data from 345 clients who completed a baseline assessment prior to participating in a health coaching intervention. Self-reported drug use and saliva drug tests were compared to determine the positive predictive value for amphetamines/methamphetamines (47.1% agreement), cocaine (43.8% agreement), and marijuana (69.7% agreement) drug tests. Exclusively relying on self-reported drug use may not be a valid measure of drug use in this population. However, we also found instances where people self-reported recent drug use that was not captured by the saliva drug test. In general, amphetamine/methamphetamine and cocaine use was adequately captured by the biological test, while marijuana use was best captured by a combination of self-report and biological data. Assessments of drug use among permanent supportive housing residents should not rely exclusively on self-reported measurements of drug use.