High prevalence of urine tampering in an office-based opioid treatment practice detected by evaluating the norbuprenorphine to buprenorphine ratio

The prevalence of urine tampering within office-based opioid treatment (OBOT) is not currently known. This study was a cross-sectional analysis of an OBOT practice in New York City that experienced both a change in provider and a change in electronic medical record software. At that time, every patient in the practice received a urine drug test for “quantitative buprenorphine metabolites.” Methods Outcomes of the first three urine drug tests were tabulated and analyzed with specific attention to the frequency of buprenorphine-positive (bup +), norbuprenorphine-negative (norbup −) samples, a pattern consistent with urine tampering. Results On the first sample 6/33 (18%) of patients submitted bup +/norbup − samples, and an additional 3 patients submitted bup +/norbup − samples on subsequent urine tests. Retention to the end of the study period among patients with bup +/norbup − samples was 33%, while in those with bup +/norbup + samples it was 96%. A scatter plot of norbuprenorphine vs. buprenorphine levels estimated that a ratio of < 0.2 indicated tampering. Conclusion Testing for buprenorphine metabolites yields valuable clinical information. The prevalence of a result pattern consistent with tampering by “urine spiking,” the addition of unconsumed buprenorphine into the urine sample, may be higher than previous estimates. Previous lower cutoffs of the norbuprenorphine:buprenorphine metabolic ratio may miss a substantial proportion of these likely tampered samples.