title: What's the agreement between self-reported and biochemical verification of drug use? A look at permanent supportive housing residents.
abstract: Self-reported substance use is commonly used as an outcome measure in treatment research. We evaluated the validity of self-reported drug use in a sample of 334 adults with mental health problems who were residing in supportive housing programs. The primary analysis was the calculation of the positive predictive values (PPVs) of self-report compared to an oral fluid test taken at the same time. A sensitivity analysis compared the positive predictive values of two self-reported drug use histories: biological testing window (ranging between the past 96h to 30days depending on drug type) or the full past 90-day comparison window (maximum length recorded during interview). A multivariable logistic regression was used to predict discordance between self-report and the drug test for users. Self-reported drug use and oral fluid drug tests were compared to determine the positive predictive value for amphetamines/methamphetamines/PCP (47.1% agreement), cocaine (43.8% agreement), and marijuana (69.7% agreement) drug tests. Participants who misreported their drug use were more likely to be older, non-White, have no medical insurance, and not report any alcohol use. In general, amphetamine/methamphetamine/PCP 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. Using the full past 90day comparison window resulted in higher concordance with the oral fluid drug test, indicating that self-reported drug use in the past 90days may be a proxy for drug use within the biological testing window. Self-report has some disadvantages when used as the sole measure of drug use in this population.
authors.affiliation: University of North Texas Health Science Center, School of Public Health, Department of Behavioral and Community Health, Fort Worth, TX, United States. Electronic address: alexis.rendon@live.unthsc.edu.
authors.forename: Alexis
authors.initials: A
authors.lastname: Rendon
authors.affiliation: University of North Texas Health Science Center, School of Public Health, Department of Biostatistics and Epidemiology, Fort Worth, TX, United States.
authors.forename: Melvin
authors.initials: M
authors.lastname: Livingston
authors.affiliation: University of North Texas Health Science Center, School of Public Health, Department of Biostatistics and Epidemiology, Fort Worth, TX, United States.
authors.forename: Sumihiro
authors.initials: S
authors.lastname: Suzuki
authors.affiliation: University of North Texas Health Science Center, School of Public Health, Department of Behavioral and Community Health, Fort Worth, TX, United States.
authors.forename: Whitney
authors.initials: W
authors.lastname: Hill
authors.affiliation: University of North Texas Health Science Center, School of Public Health, Department of Behavioral and Community Health, Fort Worth, TX, United States.
authors.forename: Scott
authors.initials: S
authors.lastname: Walters
mesh_terms: D005260:Female; D006703:Ill-Housed Persons / Q000706:statistics & numerical data*; D006798:Housing; D006801:Humans; D008297:Male; D008875:Middle Aged; D057566:Self Report; D015813:Substance Abuse Detection / Q000379:methods* / Q000706:statistics & numerical data*; D019966:Substance-Related Disorders / Q000453:epidemiology*; D013781:Texas / Q000453:epidemiology
keywords: Chronic homelessness; Self-report; Substance abuse; Supportive housing; Timeline Follow-back