A comparison of the utility of urine- and hair testing in detecting self-reported drug use among young adult opioid users

Background: Biological testing can be used to validate or detect underreported drug use. Since hair testing is increasingly used in survey research, we examined how the utility of hair testing compares to a more common method-urine testing. Methods: 532 adults (ages 18-29) reporting past-month heroin use and/or nonmedical prescription opioid use were surveyed about past-month use of various drugs. Participants were urine-tested and the majority (79.3%) provided a hair sample for analysis. We examined the utility of urine vs. hair-testing in detecting past-month use of various drugs. Results: Compared to hair testing, urine testing was able to confirm higher proportions of self-reported use of heroin/opioids (85.5% vs. 80.9%), marijuana (73.9% vs. 22.9%), benzodiazepines (51.3% vs. 15.1%), and methadone (77.0% vs. 48.7%), while hair testing was more likely to detect reported cocaine use (66.3% vs. 48.0%) (Ps < .01). Compared to hair testing, urine testing was more likely to detect unreported use of marijuana (11.3% vs. 0.9%), and benzodiazepines (14.4% vs. 5.4%), and hair testing was more likely to detect unreported use of cocaine (27.0% vs. 5.8%) and oxycodone (19.7% vs. 1.4%) (Ps < .001). When added to urine testing, hair testing increased detection of reported and non-reported use of cocaine and oxycodone ranging from 14 to 22%. Conclusions: While hair testing is efficacious in detecting drug use in wide window periods (e.g., past-year use), it is less efficacious than urine testing when testing for past-month use of select drugs among opiate/opioid users. However, hair testing is particularly efficacious in detecting unreported use of cocaine and/or oxycodone.