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HIV pre-exposure prophyalxis (PrEP) might lead individuals to view serodisclosure as unnecessary. We examined the prevalence of non-disclosure and lack of knowledge of partner status in a global cohort of men who have sex with men (MSM) and transgender women (TW) enrolled in the iPrEx Open Label Extension (OLE). We calculated prevalence ratios by fitting a logistic model and estimating predicted probabilities using marginal standardization. Prevalence of non-disclosure and lack of knowledge of partner status were highest in Thailand (73% and 74%, respectively) and lowest in the USA (23% and 37%, respectively). In adjusted analyses, PrEP use was not significantly associated with non-disclosure or lack of knowledge of partner status (p-values>0.05). We found that relationship characteristics were significantly associated with both outcomes. Non-disclosure was higher among casual (adjusted prevalence ratio [aPR] 1.54, [95% confidence interval 1.24-1.84]) and transactional sex partners (aPR 2.03, [1.44-2.62]), and among partners whom participants have known only minutes or hours before their first sexual encounter (aPR 1.62, [1.33-1.92]). Similarly, participants were less likely to know the HIV status of casual partners (aPR 1.50, [1.30-1.71]), transactional sex partners (aPR 1.62, [1.30-1.95]), and those they have known for only days or weeks (aPR 1.13, [0.99-1.27]) or minutes or hours (aPR 1.27, [1.11-1.42]). Our findings underscore the role of dyadic factors in influencing serodisclosure. Comprehensive risk reduction counseling provided in conjunction with PrEP that address relationship characteristics are needed to help patients navigate discussions around HIV status.

Background: As pre-exposure prophylaxis (PrEP) with tenofovir disoproxil fumarate and emtricitabine for the prevention of HIV infection is rolled out internationally, strategies to maintain effectiveness and to minimise adverse effects merit consideration. In this study, we aimed to assess reductions in renal function and predictors of renal toxicity in a large open-label study of PrEP., Methods: As part of the iPrEx open-label extension (OLE) study, men who have sex with men or transgender women aged 18-70 years who were HIV negative and had participated in three previous PrEP trials from Brazil, Ecuador, Peru, South Africa, Thailand, and the USA were enrolled into an open-label PrEP study. There were no restrictions on current renal function for enrolment into iPrEx OLE, in which participants were given combination tablets of tenofovir disoproxil fumarate (300 mg) and emtricitabine (200 mg) and advised to take one tablet per day. At follow-up sessions every 12 weeks, participants' creatinine clearance on PrEP was estimated and in a subset of participants, hair samples were collected to measure tenofovir and emtricitabine concentrations (a measure of adherence and exposure) via liquid-chromatography-tandem-mass-spectrometry. Reductions in creatinine clearance from baseline were calculated and predictors of decline were identified by use of multivariate models. iPrEx is registered with ClinicalTrials.com, number NCT00458393., Findings: Baseline characteristics were similar between all participants in iPrEx-OLE (1224 participants with 7475 person-visits) and those participating in the hair substudy (220 participants with 1114 person-visits). During a median of 72 weeks, the mean decline in creatinine clearance was -2·9% (95% CI -2·4 to -3·4; p trend <0·0001), but declines were greater for those who started PrEP at older ages: participants aged 40-50 years at baseline had declines of -4·2% (95% CI -2·8 to -5·5) and participants older than 50 years at baseline had declines of -4·9% (-3·1 to -6·8). In multivariate models, age and baseline creatinine clearance less than 90 mL/min predicted declines in renal function. We identified a monotonic association between percentage decrease in creatinine clearance and the number of doses of tenofovir disoproxil fumarate and emtricitabine taken per week, as estimated by hair concentrations of tenofovir and emtricitabine (p trend =0·008)., Interpretation: Our data suggest that the frequency of safety monitoring for PrEP might need to be different between age groups and that pharmacological measures can monitor for toxic effects as well as adherence., Funding: National Institutes of Health., (Copyright © 2016 Elsevier Ltd. All rights reserved.)