Injection Drug Use Associated with HIV Treatment Non-Adherence

Studies have demonstrated a relationship between injection drug use and worse HIV treatment outcomes. Using data from the Swiss HIV Cohort Study, the authors investigated how both injection drug use (IDU) and non-injection drug use (non-IDU, including cannabis) influence antiretroviral therapy (ART) adherence, lack of retention in HIV care (“dropout”), virologic suppression, and all cause mortality.

• The majority of non-IDU was cannabis use (948 or 14% of all participants), followed by cocaine (228, 4% of all participants).
• In multivariable analyses, current IDU was most strongly associated with dropout (relative risk [RR], 2.88). Receipt of methadone with concomitant IDU was most strongly associated with mortality (RR, 5.03). Current IDU was associated with worse ART adherence and more treatment interruptions.
• Patterns of non-IDU associated with dropout included non-IDU weekly or daily (RR, 1.58), and people with past IDU who have current non-IDU monthly or less (RR, 1.94). Patterns of drug use associated with mortality included non-IDU daily or weekly (RR, 1.97), and people with past IDU who have current non-IDU weekly or daily (RR, 2.45).
• Weekly or daily cannabis use was associated with dropout (RR, 1.7) and mortality (RR, 2.28).
• Investigators found no association between non-IDU and ART/retention outcomes.

Comments:

This study is consistent with prior literature that suggests worse outcomes for HIV-infected individuals who have current IDU. Here, non-IDU was also associated with worse outcomes, but with lower relative risk. It should be noted that non-IDU was primarily cannabis use, and while cannabis was analyzed on its own, other non-IDU was not analyzed as a separate group. The analysis suggesting that regular cannabis use is associated with both dropout and mortality was not adjusted for other drug use, which may substantially confound the relationship. Interventions focusing on substance use in HIV should continue to focus on IDU; however, the role of non-IDU, including cannabis, should also be considered. Future investigations might benefit from separate analyses of cannabis and other non-IDUs.

Jessica S. Merlin, MD, MBA

Reference:

Weber R, Huber M, Battegay M, et al. Influence of noninjecting and injecting drug use on mortality, retention in the cohort, and antiretroviral therapy, in participants in the Swiss HIV Cohort
Study. HIV Med. 2014 [Epub ahead of print]. doi: 10.1111/hiv.12184.