November 16, 2018
2 min read

Substance use does not lower adherence to PrEP in MSM

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Study findings showed that substance use does not affect adherence to HIV pre-exposure prophylaxis, or PrEP, among men who have sex with men or transgender women.

“Over the past 2 decades, substance use, in particular use of stimulants, such as methamphetamine, remains prevalent among men who have sex with men (MSM) and transgender women in the United States,” Martin Hoenigl, MD, a researcher at the University of California, San Diego, and colleagues wrote. “Alcohol, stimulant use, and injection drug use are independently associated with increased risk behavior and HIV acquisition among MSM and transgender women. Thus, HIV-uninfected MSM and transgender women with substance use might represent ideal candidates for PrEP.”

PrEP can reduce the risk for HIV infection in people who are at high risk by up to 92% when taken consistently, according to the CDC. Hoenigl and colleagues hypothesized that MSM and transgender women who used substances would have lower levels of PrEP adherence. They investigated this association among participants in the California Collaborative Treatment Group 595 Study, a randomized controlled trial that evaluated individualized text messaging to improve PrEP adherence.

Between February 2014 and February 2016, participants received PrEP, safety monitoring, HIV/STI testing and counseling for risk reduction at four medical centers in southern California. Hoenigl and colleagues assessed baseline and ongoing substance use over a 48-week period and measured PrEP adherence by using dried blood spots (DBS).

Of the 394 participants in the study who finished the baseline substance use questionnaire — 391 MSM and three transgender women — 72% (n = 288) reported substance use and 83% (n = 327) reported alcohol use. Overall, 89% of participants had adequate DBS tenofovir diphosphate levels at week 12, decreasing to 83% at week 48, according to Hoenigl and colleagues.

They reported finding no significant differences in the primary adherence outcome between participants with or without ongoing substance or alcohol use. In other findings, patients with ongoing substance use had higher levels of depressive symptoms than those without, and 39% (n = 152) of all participants were diagnosed with an STI during the study, with STIs occurring more frequently in participants who used stimulants, according to Hoenigl and colleagues.

“Three main findings are evident. First, substance use was not associated with decreased adherences to PrEP, as measured by [tenofovir-diphosphate] in DBS. Second, baseline frequent substance use was associated with higher likelihood of study completion. Third, baseline stimulant use was strongly associated with higher rates of incident STIs during the study, suggesting greater sexual risk behavior in users of stimulant substances,” the authors concluded. “Taken together, these findings indicate that substance use should not be used as a reason to withhold PrEP because of concerns about adherence.” – by Caitlyn Stulpin

Disclosures: The authors report no relevant financial disclosures.