CROI 2016 Abstract eBook

Abstract Listing

Poster Abstracts

Methods: We conducted a cohort study of Kaiser Permanente Northern California members initiating PrEP from July 2012 through December 2014. Follow-up was from the first dispensing of FTC/TDF until the earliest of PrEP discontinuation (i.e., ≥120 days without medication), health plan disenrollment, HIV seroconversion, death, or end of study (June 2015). Refill adherence was calculated by dividing days’ supply dispensed by total days between first and last FTC/TDF fill during follow-up among patients with ≥2 fills. We used chi-square tests to examine low adherence (<60%, consistent with taking <4 of 7 doses per week) by age, gender, and race/ethnicity. Multivariable log-binomial regression was used to estimate risk ratios (RRs) for factors associated with discontinuation. Results: Among 972 individuals who initiated PrEP, there were 850 person-years of follow-up, with a mean of 0.9 years per person. The mean age at PrEP initiation was 37 years (range 18-68), and 98% of PrEP users were men. The majority were White (65%), followed by Hispanic (11%), Asian (9.7%), and Black (4.0%). Among 915 individuals with ≥2 fills, mean adherence was 92% (median 97%; interquartile range: 90%-100%), with >80% adherence in all demographic subgroups. Only 27 (3.0%) PrEP users had <60% adherence, with a higher proportion with low adherence in patients aged <30 vs. ≥30 years (5.7% vs. 2.0%, P =0.005) and in Blacks/Hispanics vs. other racial/ethnic groups (6.6% vs. 2.3%, P =0.007); the rarity of low adherence precluded multivariable analysis of this outcome. PrEP was discontinued by 219 (23%) individuals. There were no differences in discontinuation by age or race/ethnicity, but women were over twice as likely to discontinue than men (RR 2.4, 95% confidence interval: 1.6-3.6; P <0.001). There were no seroconversions during PrEP use; however, there were 2 new HIV infections in Black and Hispanic men aged <30 years who had discontinued PrEP. Conclusions: There were no HIV infections among active PrEP users during 850 person-years of follow-up, which is consistent with the high adherence observed in this population. Given the two seroconversions after PrEP discontinuation, there is a critical need for strategies to support continuation of PrEP throughout periods of HIV risk. 895 National HIV Incidence Estimates Among STI Clinic Attendees in England, UK Adamma Aghaizu 1 ; Gary Murphy 1 ; JenniferTosswill 1 ; Daniela De Angelis 2 ; HelenWard 3 ; Gwenda Hughes 1 ; Noel O. Gill 1 ;Valerie Delpech 1 1 PH England, London, UK; 2 Med Rsr Council Biostatistics Unit, Cambridge, UK; 3 Imperial Coll London, London, UK Background: Currently, in England, national estimates for HIV incidence exist only for MSM. These are based on back-calculation and simulation models, both of which do not take migration into account which is necessary in particular for ethnic minority populations. Here we used a recent infection testing algorithm (RITA), consisting of biomarker, epidemiological and clinical information to examine national trends in incidence for all persons attending sexual transmitted infection (STI) clinics, where four of five people with HIV are diagnosed. Methods: For each year, national HIV case report information from between 125 and 150 of the 210 STI clinics in England was linked to biological and testing information. The AxSYM assay, modified to determine antibody avidity, was used to classify HIV infections as likely recently acquired. A recency index cut-off of 0.8 was used, giving an estimated mean duration of recent infection of 181 days. All cases with a viral load <400 copies/mL or on ART or with an AIDS diagnosis were classified as longstanding infections. We calculated a 1.9% proportion false recent using known longstanding infections and estimated HIV incidence using the WHO formula for cross-sectional studies. Results: From 2009 to 2013, between 161,000 and 231,000 heterosexuals (including between 9,700 and 26,000 black Africans) and 19,000 and 55,000 MSM attending STI clinics each year were included in analyses. National estimates of HIV incidence among heterosexuals remained stable between 0.03% (95% C.I.0.02%-0.05%) and 0.05% (0.03%-0.05%), whilst among black African heterosexuals it was 4-5-fold higher, increasing slightly (although non-significantly) from 0.15% (0.05%-0.26%) in 2009 to 0.19% (0.04%-0.34%) in 2013. Incidence among MSM was highest and increased (non-significantly) from 1.24% (95%C.I 0.96-1.52%) to 1.46% (95% C.I 1.23%-1.70%) after a peak of 1.52% (95%C.I 1.30%- 1.75%) in 2012. Conclusions: These are the first national HIV incidence estimates for both heterosexual and MSM populations in the UK attending STI clinics. They show MSM and black Africans remain disproportionately at risk of HIV infection. Our novel method based on a biomarker and surveillance data provides timely and accurate HIV incidence estimates which are critical in monitoring the population impact of prevention programmes including pre-exposure prophylaxis. 896 High HIV Incidence in Men Attending New York City LGBT and STD Clinics, 2009-2012 Background: HIV incidence is notoriously difficult to measure accurately using cross-sectional laboratory-based algorithms and/or statistical modeling. The ideal method – direct measurement of seroconversions in a cohort of seronegative persons followed over time—is logistically challenging, expensive and difficult to implement on a population basis. Methods: We assembled a cohort of initially seronegative persons undergoing HIV diagnostic testing at the public health laboratory (PHL) in New York City. Persons were followed from the date of their first negative test on or after January 1, 2009, through the date of their first positive test, death, or December 31, 2012. Seroconversions were identified in the PHL database and through matching with the HIV surveillance registry. Results: Of the 74,463 unique individuals with an initially negative test result, there were 18,197 persons, including 12,854 women (99% aged 15-44) and 5,246 men, with at least one subsequent negative or positive test at the PHL, or at least one subsequent positive test at another venue. The repeat tester cohort had 34,445.9 total person-years of follow-up, 447 seroconversions (56.2% at the PHL and 43.8% at other sites) and an incidence rate of 1.30/100 py (1.18,1.42). Incidence was elevated in men overall (5.7/100 py [95% CI 5.2, 6.2]; adjusted hazard ratio for male-to-female 43.9 [95% CI 29.9,64.4]) and highest among men whose specimens were submitted from clinics serving the LGBT community (14.2/100py [10.1, 18.2]), men attending STD clinics (5.8/100 py [5.1, 6.4]) and young (aged <30) black (8.5/100py [7.0, 10.1] and white men (6.3/100 py [4.9, 7.8]). Conclusions: Incidence in men attending LGBT clinics was 12 times higher than incidence in all repeat testers and 2.5 times higher than incidence in men overall and men tested in STD clinics. The high male-to-female hazard ratio likely reflects the inclusion of many women tested during pregnancy. Incidence was also elevated among young (aged <30) black and white men. Data from this large cohort can be used to target local prevention resources, including PrEP and nPEP, to appropriate venues and populations. Figure: Time to seroconversion – all testers, male and female, and men attending LGBT and STD clinics vs. men attending all other providers Lucia V. Torian 1 ; Lisa A. Forgione 1 ;William Duffy 1 ; Bisrom Deocharan 1 ; Robert Pirillo 2 ; OrlinTrochev 2 ; Amado Punsalang 2 ; Anthony Muyombwe 3 1 New York City Dept of Hlth, Long Island City, NY, USA; 2 New York City Dept of Hlth, New York, NY, USA; 3 Connecticut Dept of Hlth, Hartford, CT, USA

Poster Abstracts

100%

All testers, male and female

Men attending other providers

90%

Men attending LGBT and STD clinics

Time to seroconversion(%)

80%

0

1

2

3

4

Years after negative test

376

CROI 2016