Opioid overdose more likely in patients who discontinue or don’t start treatment

An increased risk of overdose events in the next 24 weeks is seen in patients with opioid use disorder seeking medication treatment who fail to initiate or discontinue medication and those who report using benzodiazepine at baseline, reports a study.

A group of researchers assessed the adverse event logs, including overdose events, from three trials (n=2,199). Using survival analysis with time-dependent Cox proportional hazard models, they compared the overall risk of having an overdose event in the 24 weeks following randomization for each study arm (one methadone, one naltrexone, and three buprenorphine groups).

Of the participants, 39 had at least one overdose event by week 24. The frequency of an overdose event for each study arm was 15 (5.30 percent) among 283 patients on naltrexone, eight (1.51 percent) among 529 patients on methadone, and 16 (1.15 percent) among 1,387 patients on buprenorphine.

Interestingly, more than one in four (27.9 percent) of patients assigned to extended-release naltrexone did not initiate medication, resulting in an overdose rate of 8.9 percent (7/79), compared with 3.9 percent (8/204) among those who initiated naltrexone.

A proportional hazard model showed no significant effect of naltrexone assignment, when controlled for sociodemographic and time-varying medication adherence variables and baseline substance use.

Notably, the chances of having an overdose event were markedly higher among patients with baseline benzodiazepine use (hazard ratio [HR], 3.36, 95 percent confidence interval [CI], 1.76‒6.42) and those who either were never inducted on their assigned medication (HR, 6.64, 95 percent CI, 2.12‒19.54) or stopped their medication after initial induction (HR, 4.04, 95 percent CI, 1.54‒10.65).