Professor Matt Hickman

Matt Hickman is Head of Population Health Sciences and Deputy Head of Bristol Medical School, Professor in Public Health and Epidemiology at Bristol, NIHR Senior Investigator, and Honorary Public Health Consultant at Bristol City Council and Public Health England. He is the director of National Institute Health Research (NIHR) Health Protection Research Unit on Evaluation of Interventions, and member of NIHR School of Public Health Research.  He is deputy regional editor of Addiction, and a member of the Scientific Committee of European Monitoring Centre on Drugs and Drug Addiction (EMCDDA), WHO Technical Advisory Group on alcohol and drug epidemiology, and International Network on Hepatitis Care for Substance Users (INHSU).

The impact of opioid agonist treatment delivered in different settings on all-cause mortality and specific causes of death: A systematic review and meta-analysis

Aims: To estimate the impact of time in OAT on all-cause and cause-specific mortality.

Methods: All observational studies that collected data on all-cause or cause-specific mortality among people with opioid dependence in and out-of-OAT and randomised controlled trials (RCTs) were included.

We followed GATHER, PRISMA and MOOSE guidelines. Data on study, participant and treatment characteristics were extracted; person-years, and all-cause and cause-specific mortality. Crude mortality rates and rate ratios (RRs) were pooled using random-effects meta-analyses.

Results: 15 eligible RCTs, N=3,852 participants; 36 primary cohort studies, N=749,634. Cohort studies found all-cause mortality during OAT more than halved compared to time out-of-OAT (RR=0.47; 95%CI 0.42-0.53). This effect was similar by gender, age, location, HIV, or HCV status, and people who inject. Effects were not different for methadone (RR=0.47; 95%CI 0.41-0.54) versus buprenorphine (RR=0.34; 95%CI 0.26-0.45). There was lower risk of drug-related, suicide, alcohol-related, cancer, and cardiovascular mortality during OAT. In the first four weeks of methadone, all-cause mortality and drug-related poisoning was almost double that in the remainder of OAT (not so for buprenorphine). It was six-times higher in the four weeks following OAT cessation, remaining double the rate for remainder of time out-of-OAT. Evidence suggests an extremely strong protective effect of OAT when incarcerated and after release from incarceration, particularly suicide and overdose.

Conclusions: OAT is associated with a reduction in multiple causes of death. Nonetheless, access remains limited, and coverage too low globally. More refined linkage studies are needed to make a step-change in evidence on impact of OAT in UK and elsewhere.
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