Among a cohort of men who have sex with men in a pre-exposure prophylaxis (PrEP) adherence trial, syphilis requiring treatment was associated with white coat dosing (increased PrEP adherence immediately preceding study visits) when compared with participants with optimal drug concentrations. The findings highlight the need for identifying and reducing barriers to PrEP adherence.

Post-exposure prophylaxis (PEP) is a promising but under-utilized strategy for HIV prevention in high-risk populations. Between March 2010 and June 2011, two community-based clinics in Los Angeles County provided PEP in a pilot program to 267 unique individuals. Courses were primarily dispensed to men who have sex with men (84%) and consisted overwhelmingly of a three-drug antiretroviral therapy regimen containing two nucleoside reverse transcriptase inhibitors and either an integrase inhibitor (raltegravir) or a boosted protease inhibitor (lopinavir/ritonavir). Approximately 64% of all PEP courses were followed for at least 12 weeks, and seven individuals seroconverted. Of the seven seroconversions, six had subsequent re-exposure. The low rate of PEP failure calls for expanded funding for PEP in other jurisdictions.

PrEP's potential benefit for men who have sex with men (MSM) who use stimulants may be limited by adherence or prescriber willingness to recommend PrEP due to concerns of non-compliance. Using data from PATH-PrEP, a 48-week study evaluating PrEP for MSM in Los Angeles, we modeled an interaction between stimulant use and condomless sex with multiple partners (CAS-MP) on prevention-effective dried blood spot tenofovir-diphosphate concentrations. At week 4, participants reporting stimulant use and CAS-MP had a decreased odds of prevention-effective adherence compared to non-stimulant use and non-CAS-MP (AOR 0.15, 95% CI 0.04-0.57). From week 4-48, participants reporting stimulant use and CAS-MP had increased odds of prevention-effective adherence (AOR 1.06 per week, 95%CI 1.01-1.12). Participants reporting CAS-MP without stimulant use had no significant change in prevention-effective adherence (AOR 0.99 per week, 95%CI 0.96-1.02). Stimulant use moderated the association of CAS-MP on prevention-effective PrEP adherence over time.

PrEP's potential benefit for men who have sex with men (MSM) who use stimulants may be limited by adherence or prescriber willingness to recommend PrEP due to concerns of non-compliance. Using data from PATH-PrEP, a 48-week study evaluating PrEP for MSM in Los Angeles, we modeled an interaction between stimulant use and condomless sex with multiple partners (CAS-MP) on prevention-effective dried blood spot tenofovir-diphosphate concentrations. At week 4, participants reporting stimulant use and CAS-MP had a decreased odds of prevention-effective adherence compared to non-stimulant use and non-CAS-MP (AOR 0.15, 95% CI 0.04-0.57). From week 4-48, participants reporting stimulant use and CAS-MP had increased odds of prevention-effective adherence (AOR 1.06 per week, 95%CI 1.01-1.12). Participants reporting CAS-MP without stimulant use had no significant change in prevention-effective adherence (AOR 0.99 per week, 95%CI 0.96-1.02). Stimulant use moderated the association of CAS-MP on prevention-effective PrEP adherence over time.