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

UNLABELLED

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.