Similarities and changes between 15- and 24-year survival and retention rates of patients in a large medical-affiliated methadone maintenance treatment (MMT) center

Background: Environmental and social trends and patients’ characteristics may affect predictors for methadone maintenance treatment (MMT) outcome. Methods: We have expanded our previous study of predictors for MMT outcome (from 619 to 890 patients) and the study period (from 15 to 24 years). Survival and retention in MMT since admission to the MMT clinic (6/1993–6/2016) and until death or study closure (6/2017) were compiled and analyzed. Results: Of 890 patients ever admitted (10,146.9 person-years (py)), 237 passed away (116 while in MMT). The mortality rate did not differ between those who stayed or left (2.6 vs. 2.1 per 100 py, p = 0.1), but it was lower among those who stayed ≥1 year during any admission (2.1 vs. 3.3 per 100 py, respectively, p = 0.004). Age <40 years, no hepatitis C or B, no HIV, and no benzodiazepine abuse after one year predicted longer survival (multivariate analyses). No opiate or benzodiazepine abuse after one year, methadone dose ≥100 mg/d, no DSM-IV-TR Axis II diagnosis only, and no direct hospital referral predicted longer retention. Cocaine abuse predicted poor retention and survival among 271 patients admitted during the extended part of the study period. Conclusions: Predictors for retention (associated with MMT outcome) and mortality (associated with pre-treatment comorbidity) after 24 years were similar to those after 15 years. Cocaine abuse as a predictor of both poor retention and poor survival in the later period may reflect the escalating trend for cocaine abuse and should be studied if related to other unmonitored substances.