HIV antiretroviral prophylaxis for injecting drug users

Abstract

Antiretroviral prophylaxis has the potential to be an effective component of HIV prevention in high-risk populations. The efficacy reported in people who inject drugs in Kachit Choopanya and colleagues' study1Choopanya K Martin M Suntharasamai P et al.Antiretroviral prophylaxis for HIV infection in injecting drug users in Bangkok, Thailand (the Bangkok Tenofovir Study): a randomised, double-blind, placebo-controlled phase 3 trial.Lancet. 2013; 381: 2083-2090Summary Full Text Full Text PDF PubMed Scopus (958) Google Scholar is striking. We applaud the focus on injecting drug users, but urge cautious interpretation of these findings. The injecting drug users in this study were relatively low risk. At baseline, only 22% reported injecting drugs weekly and 18% shared needles; both risk behaviours declined further with time. HIV incidence was low (less than 1 per 100 person-years). These results should not be generalised to populations with high-risk injection behaviours or high HIV incidence. Crucially, the study does not clearly address whether antiretroviral prophylaxis in injecting drug users prevented parenteral transmission of HIV. A second issue is that the intervention effect only occurs after 3 years. Roughly a fourth of the sample group dropped out of the study by 3 years, so individuals at high risk could have been lost to follow-up or exited the study prematurely. The marked absence of effect before 3 years suggests an absence of short-term benefits of antiretroviral prophylaxis. Finally, the study was done primarily with directly observed therapy, which might be largely responsible for the observed effect. However, widespread adoption of directly observed antiretroviral prophylaxis seems unlikely in most settings with high HIV incidence. On the basis of these observations, we strongly suggest that antiretroviral prophylaxis in injecting drug users is not yet appropriate for widespread implementation. We declare that we have no conflicts of interest. Antiretroviral prophylaxis for HIV infection in injecting drug users in Bangkok, Thailand (the Bangkok Tenofovir Study): a randomised, double-blind, placebo-controlled phase 3 trialIn this study, daily oral tenofovir reduced the risk of HIV infection in people who inject drugs. Pre-exposure prophylaxis with tenofovir can now be considered for use as part of an HIV prevention package for people who inject drugs. Full-Text PDF HIV antiretroviral prophylaxis for injecting drug users – Authors' replyMichael Hudgens and Stephen Cole, and William Miller and colleagues note that the Kaplan-Meier estimates1 for the two groups were similar for the first 36 months of follow-up; however, a formal test for the proportional hazards assumption found that efficacy did not differ by time on study (p=0·15). Additionally, there is no biological reason to expect an absence of short-term benefit, and results from other pre-exposure prophylaxis trials do not lend support to this assumption.2–4 We did the test for equal probability at 60 months using trial data and found 52% efficacy (95% CI 10–75, p=0·02). Full-Text PDF