Comparative effectiveness of urine drug testing schedules alongside opioid agonist treatment: Emulation of a population-based target trial in British Columbia, Canada.

Background and aim: Urine drug testing is often utilized alongside opioid agonist treatment to assess client progress by validating self-reported substance use, monitoring for diversion and supporting clinical decisions for take-home dosing. However, there is a paucity of evidence to support the practice of urine drug testing. We aimed to determine the association of alternative urine drug testing frequencies with opioid agonist treatment discontinuation, compared with no monitoring, among individuals receiving methadone or buprenorphine/naloxone treatment.

Design: Population-based retrospective cohort study and target trial emulation based on nine-linked administrative databases.

Setting: British Columbia, Canada, between 1 January 2010 and 17 March 2020.

Participants: Individuals with no history of cancer or palliative care, aged 18 or older and no indication of pregnancy who initiated methadone or buprenorphine/naloxone. A total of 18 988 methadone and 11 910 buprenorphine/naloxone recipients were included in the incident user design (individuals with no past opioid agonist treatment experience).

Measurements: We used a clone-censor-weight approach to estimate hazard ratios with 95% compatibility ("confidence") intervals for treatment discontinuation (lasting at least 5 and 6 days for methadone and buprenorphine, respectively) and all-cause mortality on treatment within 12 months for static urine drug testing strategies.

Findings: Under static monitoring strategies, weekly urine drug testing was associated with a slightly reduced risk of discontinuation in the first year of continuous retention in treatment [methadone: adjusted hazard ratio (aHR) = 0.96, 95% compatibility interval (CI) = (0.95-0.98); buprenorphine/naloxone: aHR = 0.95 (0.94-0.97)] compared with no monitoring. The estimated associations of weekly urine drug testing with all-cause mortality were similar in size but extremely imprecise [methadone: aHR = 0.95 (0.78-1.15), buprenorphine/naloxone: aHR = 0.99 (0.62-1.58)]. Less frequent testing demonstrated no observed difference on treatment discontinuation or all-cause mortality compared with no monitoring.

Conclusion: Compared with no urine drug testing, weekly urine drug testing may be associated with improved opioid agonist treatment retention; however, the high costs attributable to frequent testing may not be cost-effective and requires further evaluation. There was no improvement associated with less frequent testing compared with no monitoring.