CROI 2017 Abstract e-Book

Abstract eBook

Poster and Themed Discussion Abstracts

Conclusion: While substance users had increased STI rates, indicating higher risk behavior, PrEP adherence was not lowered by substance or alcohol use. In fact, likelihood to reach TFV-DP levels above the cut-offs appeared to be higher in participants with substance use suggesting that these individuals may have insight into HIV risk and appropriately be more diligent with PrEP adherence. 978 OLDER AGE ASSOCIATED WITH BOTH ADHERENCE AND RENAL DECLINE IN THE PREP DEMO PROJECT Monica Gandhi 1 , Peter Bacchetti 1 , Catherine A. Koss 1 , Chengshi Jin 1 , Howard Horng 1 , Richard Elion 2 , Michael Kolber 3 , Stephanie E. Cohen 4 , Susan Buchbinder 4 , Albert Y. Liu 4 1 Univ of California San Francisco, San Francisco, CA, USA, 2 The George Washington Univ, Washington, DC, USA, 3 Univ of Miami, Miami, FL, USA, 4 San Francisco Dept of Pub Hlth, San Francisco, CA, USA Background: Pharmacokinetic (PK) metrics (drug levels in a matrix such as plasma, dried blood spots, or hair) provide objective measures of adherence and exposure to TDF/FTC- based PrEP. As PrEP use expands in diverse, “real-world” populations, PK metrics from demonstration projects can be used to assess predictors of adherence to and safety of PrEP. Methods: The US PrEP Demonstration Project (PrEP Demo) enrolled HIV-negative MSM and transwomen (TGW) in San Francisco, Miami and DC and provided 48 weeks of TDF/ FTC-based PrEP. Tenofovir (TFV) and FTC levels were measured in hair in a subset of participants using validated LC/MS-MS assays. Multivariate logistic regression models were used to analyze predictors of TFV hair levels ≥0.023 ng/mg, consistent with ≥4 doses of PrEP/week. The associations of time-dependent factors, including exposure, with visit-to-visit changes in GFR estimated by MDRD were assessed using linear mixed models. Results: From 10/2012-1/2014, 557 MSM and TGW enrolled in PrEP Demo. 280 participants (50% of total) provided hair. Among hair study participants, median age was 34 (range 19-65); 23% identified as Latino; 78%White, 5% Black, 9% Asian, 17% other; 99%MSM; 79% reported condomless receptive anal sex; 14.8% used amphetamines in the past 3 months; median baseline GFR was 98 ml/min/1.73m2. TFV hair levels were consistent with ≥4 PrEP doses taken/week in 82% of 876 person-visits at which hair was collected. Predictors of ≥4 doses/week included older age (OR 1.42 per decade, 95% CI 1.0-2.0, p=0.05); condomless receptive anal sex with a known HIV+ partner (OR 2.3, 95% CI 1.4-4.5, p=0.01); and amphetamine use (OR 2.5, 95% CI 0.93-6.5, p=0.07). Overall, GFR declined by median -4.2% (range -37 to +68) over 48 weeks. In a multivariate model, each decade of age was associated with -2.8% (-0.4 to -5.2, p=0.02) more decline in GFR; each 2-fold increase in baseline GFR was associated with -14.6% (-5.4 to -22.9, p=0.003) more decline; each doubling in FTC hair level was associated with -2.4% (-0.4 to -4.3, p=0.02) more decline. Hypertension and PrEP duration were not substantially associated with GFR decline. Conclusion: In this subset of PrEP Demo participants, older age, condomless sex with a known HIV+ partner, and amphetamine use were each associated with taking ≥4 doses/ week of PrEP. Older age, higher GFR at baseline, and higher TFV/FTC exposure were associated with greater declines in renal function. MSMwho initiate PrEP at older ages may require more frequent safety monitoring. 979 CHANGES IN SEXUAL BEHAVIOR AND STI DIAGNOSES AMONG MSM USING PREP IN SEATTLE, WA Michalina A. Montano , Julia C. Dombrowski, Lindley A. Barbee, Matthew R. Golden, Christine M. Khosropour Univ of Washington, Seattle, WA, USA Background: Whether and howMSMmodify sexual behaviors after initiating PrEP has not been well studied in non-research settings and is of particular importance as PrEP becomes more widely used. Methods: We measured changes in sexual behavior among MSM attending an STD clinic in Seattle, WA who initiated PrEP. Sexual behavior during prior 30 days was reported in a computer-assisted self-interview (CASI) administered at PrEP initiation and subsequent clinic visits every 3 months. Bacterial sexually transmitted infections (STI) diagnosed during the periods before and after PrEP initiation were identified via STI surveillance records. MSMwere asked about number of sexual partners, sexual positioning, and condom use with HIV-positive, HIV-negative, and unknown-status partners during the prior 30 days. We used linear regression to assess significance of behavioral trends. We describe the proportion of MSM reporting each behavior at each visit. We present the proportion of MSM diagnosed with chlamydia (CT), gonorrhea (GC), or syphilis in the 12 months prior to baseline for MSM who completed a baseline CASI, and the proportion of MSM diagnosed with CT, GC, or syphilis while taking PrEP, for those who completed at least one follow-up CASI. Results: 220 men began PrEP during Sept 2014 – June 2016, and completed the behavioral section of the baseline CASI. Mean age of participants was 31 (SD: 8.5), and 63%were white. Mean number of sex partners and proportion of sex with each type of partner was stable during the study period (Table). The proportion of men reporting never using condoms for any anal sex or never using condoms during receptive anal intercourse with HIV-positive partners increased over the study period, but there were no clear trends with other position and partner serostatus combinations. 24% of men were diagnosed with GC, 17%with CT, and 19%with syphilis at baseline or during the 12-months prior to PrEP initiation. Among men with at least one follow-up visit (n=76; average follow-up time = 8.6 months), 34%were diagnosed with GC, 37%with CT, and 9%with syphilis while on PrEP. Conclusion: MSM in our clinic reported decreased condom use during receptive anal intercourse with HIV-seropositive partners after initiating PrEP. The proportion of men diagnosed with CT and GC was higher in the time period after PrEP initiation, which could reflect increased risk behavior, increased detection during routine screening, or temporal increases in STD risk in the population.

Poster and Themed Discussion Abstracts

980 LABORATORY TESTING OF A US COHORT OF PRIVATELY INSURED USERS OF HIV PREP, 2011–2014 Ya-Lin A. Huang , Guoyu Tao, Taraz Samandari, Karen W. Hoover

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