Effects of medication-assisted treatment on mortality among opioids users: a systematic review and meta-analysis

Opioid use disorder (OUD) is associated with a high risk of premature death. Medication-assisted treatment (MAT) is the primary treatment for opioid dependence. We comprehensively assessed the effects of different MAT-related characteristics on mortality among those with OUD by a systematic review and meta-analysis. The all-cause and overdose crude mortality rates (CMRs) and relative risks (RRs) by treatment status, different type, period, and dose of medication, and retention time were pooled using random effects, subgroup analysis, and meta-regression. Thirty cohort studies involving 370,611 participants (1,378,815 person-years) were eligible in the meta-analysis. From 21 studies, the pooled all-cause CMRs were 0.92 per 100 person-years (95% CI: 0.79-1.04) while receiving MAT, 1.69 (1.47-1.91) after cessation, and 4.89 (3.54-6.23) for untreated period. Based on 16 studies, the pooled overdose CMRs were 0.24 (0.20-0.28) while receiving MAT, 0.68 (0.55-0.80) after cessation of MAT, and 2.43 (1.72-3.15) for untreated period. Compared with patients receiving MAT, untreated participants had higher risk of all-cause mortality (RR 2.56 [95% CI: 1.72-3.80]) and overdose mortality (8.10 [4.48-14.66]), and discharged participants had higher risk of all-cause death (2.33 [2.02-2.67]) and overdose death (3.09 [2.37-4.01]). The all-cause CMRs during and after opioid substitution treatment with methadone or buprenorphine were 0.93 (0.76-1.10) and 1.79 (1.47-2.10), and corresponding estimate for antagonist naltrexone treatment were 0.26 (0-0.59) and 1.97 (0-5.18), respectively. Retention in MAT of over 1-year was associated with a lower mortality rate than that with retention ≤1 year (1.62, 1.31-1.93 vs. 5.31, -0.09-10.71). Improved coverage and adherence to MAT and post-treatment follow-up are crucial to reduce the mortality. Long-acting naltrexone showed positive advantage on prevention of premature death among persons with OUD.

Mortality prior to, during and after opioid maintenance treatment (OMT): a national prospective cross-registry study

BACKGROUND

Opioid maintenance treatment (OMT) is generally considered to reduce mortality in opiate dependents. However, the level of mortality reduction is still uncertain. This study investigates mortality reductions in an "intention-to-treat" perspective including all dropouts. The mortality reducing effects of OMT are examined both within treatment and post-treatment. The study separates overdose and total mortality reductions.

METHODS

The study is a prospective cross-registry study with up to 7 years follow-up. All opiate dependents in Norway who applied for OMT (a total of 3789 subjects) were cross-linked with data from the death registry from Statistics Norway. Date and cause of death were crossed with dates for initiation and termination of OMT, and subjects' age and gender. A baseline was established from the waiting list mortality rate. Intention-to-treat was investigated by analysing mortality among the entire population that started OMT.

RESULTS

Mortality in treatment was reduced to RR 0.5 (relative risk) compared with pre-treatment. In the "intention-to-treat" perspective, the mortality risk was reduced to RR 0.6 compared with pre-treatment. The patients who left the treatment programme showed a high-mortality rate, particularly males.

CONCLUSIONS

OMT significantly reduces risk of mortality also when examined in an intention-to-treat perspective. Studies that evaluate effects of OMT only in patients retained in treatment tend to overestimate benefits. Levels of overdose mortality will influence the risk reduction. Cross-registry studies as the current one are an important supplement to other observational designs in this field.

Mortality in heroin-assisted treatment in Switzerland 1994-2000

BACKGROUND

A major goal of heroin-assisted treatment in Switzerland has been to reduce the drug-related mortality of heroin users. Therefore, a continuous monitoring of deaths under treatment is essential.

AIMS

To assess mortality of participants in heroin-assisted treatment in Switzerland over a 7-year period from 1994 to 2000, and to compare this mortality to the general population and to other populations of opioid users, as reported in the literature.

METHOD

Estimation of person years under heroin-assisted treatment from the complete case registry of heroin-assisted treatment in Switzerland. Estimation of standardized mortality ratios comparing the population in treatment to the Swiss population (standardized to the year 2000).

RESULTS

Over the 7-year period, the crude death rate of patients in heroin-assisted treatment, and including one month after discharge from treatment, was 1% per year. The standardized mortality ratio for the entire observation period was 9.7 (95% C.I. 7.3-12.8), with females having higher standardized mortality ratios (SMR 17.2) than males (SMR 8.4). There was no clear time trend.

CONCLUSION

Mortality in heroin-assisted treatment was low compared to the mortality rate of Swiss opioid users 1990s (estimated to be between 2.5 and 3%). It was also low compared to mortality rates of opioid users in other maintenance treatments in other countries as reported in the literature. The SMR was also lower than that reported in the only meta-analysis in the literature: 13.2 (95% C.I. 12.3-14.1). The low mortality rate is all the more noteworthy as heroin-assisted treatment in Switzerland included only refractory opioid addicts with existing severe somatic and/or mental problems.

DECLARATION OF INTEREST

No conflicts of interest declared.