Temporal and Gender Trends in Concordance of Urine Drug Screens and Self-Reported Use in Cocaine Treatment Studies

Abstract

To describe temporal trends in concordance, sensitivity, and specificity and to explore demographic trends in concordance in 2 outpatient treatment studies for cocaine dependence.

We obtained 2229 urine drug screens (UDS) from 129 individuals, along with accompanying self-use reports (SUR). Paired SUR and UDS were considered concordant if the 2 measures of cocaine use were in agreement. The sensitivity and specificity of the SUR in predicting the UDS was also estimated. To model concordance, sensitivity, and specificity as a function of time, generalized estimating equations were used. Demographic effects on concordance among subjects who achieved 100% concordance and subjects who achieved a recently proposed 70% concordance threshold were tested.

During the course of our studies, both sensitivity and concordance statistically decreased; however, specificity remained relatively constant. Median concordance for all subjects was 88%. Among all subjects, concordance varied significantly by gender, with women achieving significantly higher concordance than men (96% vs 86%). Similarly, women were almost twice as likely to achieve 100% concordance as men (42% vs 22%). Finally, 80% of participants achieved the 70% concordance threshold, and no differences among demographic groups with regards to the 70% concordance threshold were observed.

Temporal effects of concordance and sensitivity may have profound repercussions when using SUR to gauge efficacy of an experimental intervention. Furthermore, gender may differentially affect concordance. Finally, a substance abuse outcome measure that reliably combines objective and self-report data is promising, but further research is needed.