We identified 15,724 eligible individuals, among whom 7209 (45.8%) initiated buprenorphine/naloxone and 8515 (54.2%) initiated methadone. The median time to treatment discontinuation was significantly shorter among those initiating buprenorphine/naloxone rather than methadone (114 d, interquartile range:15–665 d vs. 263 d interquartile range: 32–1015 d, respectively, P<0.0001). Time on treatment increased with age in both OAT groups, with the exception of those aged 65 and older, where retention declined. Among methadone recipients, time on treatment was longer among rural relative to urban residents (372 vs. 255 d; P=0.0073), with no variation by sex. Conversely, females treated with buprenorphine/naloxone had significantly longer treatment retention than men (125 vs. 108 d; P=0.0372), with no variation by urban or rural residence.
