Monitoring patterns of substance use in drug-dependent patients

Self-report of illicit substance use versus urine toxicology results from at-risk pregnant women

INTRODUCTION

Many factors comprise a patient's decision to disclose use of drugs. Pregnant women may report drug use because they would like help with their addiction but the stigma associated with drug use may dampen their willingness to disclose. Knowledge about the accuracy of self-reported drug use as compared to urine toxicology screens can assist clinicians in the management of substance use in pregnancy.

METHOD

We compared the urine toxicology screens and self-reported use of marijuana or cocaine for 168 women enrolled in an integrated obstetrical/substance abuse treatment program. We stratified by various periods of self-reported use and race and utilized Cohen's kappa to measure overall agreement between self-report and toxicology tests.

RESULTS

Most women with a positive toxicology screen reported use in the past 28 days (78% for marijuana, 86% for cocaine). However, many women reported their most recent use to be outside of the assays' detection window (14% for marijuana, 57% for cocaine). We did not find differences in self-report for women with positive urine between Whites and non-Whites (p = 1.00). Agreement over the previous month was good (Kappa = 0.74 and 0.70 for marijuana and cocaine, respectively.).

SUMMARY

A question about use of marijuana or cocaine during the preceding month rather than the prior few days may be a better indicator of use.