METHODS: We adapted a dynamic model of HIV transmission among MSM/TW in Lima to incorporate stimulant use and increased HIV risk, suicide and CVD mortality. Among 6% to 24% of MSM/TW using stimulants (mostly cocaine), we modelled an increased risk of unprotected anal sex (RR = 1.35 [95%CI: 1.17 to 1.57]) obtained from local data, and increased risk of suicide (SMR = 6.26 [95%CI: 2.84 to 13.80]) and CVD (SMR = 1.83 [95%CI: 0.39 to 8.57]) mortality associated with cocaine use based on a global systematic review. We estimated the proportion of health harms occurring among MSM/TW who use stimulants in the next year (01-2020/01-2021). We also investigated the 10-year impact (01-2020/01-2030) of: (1) PrEP prioritization for stimulant-using MSM/TW compared to random allocation, and (2) integrating PrEP with a theoretical intervention halving stimulant-associated risk.

RESULTS: MSM/TW in Lima will experience high HIV incidence, suicide mortality and CVD mortality (1.6/100 py, and 0.018/100 py, 0.13/100 py respectively) in 2020. Despite stimulant using MSM/TW comprising an estimated 9.5% (95%CI: 7.8 to 11.5) of all MSM/TW, in the next year, 11% 95%CI (i.e. 2.5% to 97.5% percentile) 10% to 13%) of new HIV infections, 39% (95%CI: 18% to 60%) of suicides and 15% (95%CI: 3% to 44%) of CVD deaths could occur among this group. Scaling up PrEP among all stimulant using MSM/TW could prevent 19% (95%CI: 11% to 31%) more HIV infections over 10 years compared to random allocation. Integrating PrEP and an intervention to halve stimulant-associated risks could reduce new HIV infections by 20% (95%CI: 10% to 37%), suicide deaths by 14% (95%CI: 5% to 27%) and CVD deaths by 3% (95%CI: 0% to 16%) over a decade.

METHODS: 126 detoxified heroin-dependent patients, from an outpatient research clinic and detoxification programme in Malaysia, were randomly assigned by a computer-generated randomisation sequence to 24 weeks of manual-guided drug counselling and maintenance with naltrexone (n=43), buprenorphine (n=44), or placebo (n=39). Medications were administered on a double-blind and double-dummy basis. Primary outcomes, assessed by urine testing three times per week, were days to first heroin use, days to heroin relapse (three consecutive opioid-positive urine tests), maximum consecutive days of heroin abstinence, and reductions in HIV risk behaviours over 6 months. The study was terminated after 22 months of enrolment because buprenorphine was shown to have greater efficacy in an interim safety analysis. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00383045.

FINDINGS: We observed consistent, linear contrasts in days to first heroin use (p=0.0009), days to heroin relapse (p=0.009), and maximum consecutive days abstinent (p=0.0007), with all results best for buprenorphine and worst for placebo. Buprenorphine was associated with greater time to first heroin use than were naltrexone (hazard ratio 1.87 [95% CI 1.21-2.88]) or placebo (2.02 [1.29-3.16]). With buprenorphine, we also recorded significantly greater time to heroin relapse (2.17 [1.38-3.42]), and maximum consecutive days abstinent than with placebo (mean days 59 [95% CI 43-76] vs 24 [13-35]; p=0.003); however, for these outcomes, differences between buprenorphine and naltrexone were not significant. Differences between naltrexone and placebo were not significant for any outcomes. HIV risk behaviours were significantly reduced from baseline across all three treatments (p=0.003), but the reductions did not differ significantly between the three groups.