CROI 2016 Abstract eBook

Abstract Listing

Poster Abstracts

1054 Optimal Rollout of Treatment As Prevention in Africa: Efficiency Versus Equity Brian J. Coburn; Justin Okano ; Sally Blower Univ of California Los Angeles, Los Angeles, CA, USA

Background: WHO, and UNAIDS, have proposed using “treatment as prevention” (TasP) to eliminate HIV in sub-Saharan Africa (SSA). We design treatment allocation strategies for TasP based on different optimization criteria: maximizing efficiency in prevention versus ensuring equity in access to treatment. Strategies are calculated in terms of the division of a supply of treatment among, and within, healthcare districts (HCDs). We focus on Lesotho, where HIV prevalence in the general population is 40% and treatment coverage ~30%. Methods: We use kriging and adaptive bandwidth kernel density estimation to construct a concentration of infection (CoI) country-level map of the HIV epidemic. We use georeferenced HIV-testing data from~7,000 individuals, and high-resolution demographic data. We then use the CoI map and optimization techniques to calculate, and compare, treatment allocation strategies that maximize either efficiency or equity. Results: Our CoI map shows the geographic location of all HIV-infected individuals (15 to 49 years old) in Lesotho. We estimate there are ~188,000 infected individuals; ~70% live in rural areas where the average CoI is 4-10 infected individuals/km 2 , 30% live in urban areas where there are more than 400 infected individuals/km 2 . We found significant differences in allocation strategies depending upon whether the objective was to maximize efficiency in prevention or to ensure equity in access to treatment. More treatment is needed to maximize efficiency than to achieve equity in access in HCDs with a high CoI. The converse occurs in HCDs with a low CoI: more treatment is needed for equity than efficiency. Conclusions: Our results have significant implications for rolling out TasP, and eliminating HIV in SSA. Our results apply to other countries in SSA with generalized HIV epidemics and a large rural population. Our results clearly show it will not be possible to maximize the efficiency of TasP and to ensure equity in access to treatment. Choosing to maximize efficiency will be more beneficial for uninfected individuals in urban areas: their risk of infection would be reduced. Choosing to ensure equity in access will be more beneficial for HIV-infected individuals in rural areas: their mortality risk would be reduced. Choosing to maximize efficiency would increase the probability of eliminating HIV, but would exacerbate the already significant health disparities between urban and rural communities. 1055 Modeled Effectiveness of Nondaily PrEP Based on Sex Coverage Data FromHPTN067 ADAPT Dobromir T. Dimitrov 1 ; Kate M. Mitchell 2 ; James P. Hughes 3 ; Deborah Donnell 1 ; Linda-Gail Bekker 4 ; Robert Grant 5 ; Marie-Claude Boily 2 1 Fred Hutchinson Cancer Rsr Cntr, Seattle, WA, USA; 2 Imperial Coll London, London, UK; 3 Univ of Washington, Seattle, WA, USA; 4 Desmond Tutu HIV Cntr, Cape Town, South Africa; 5 Univ of California San Francisco, San Francisco, CA, USA Background: Non-daily PrEP dosing is a strategy that may be effective if sufficient PrEP doses correspond with sexual exposure. HPTN 067 ADAPT compared the feasibility of non- daily PrEP dosing regimens in populations at high risk. We modeled the reduction in HIV incidence and the number of pills that would be needed under different dosing regimens. Methods: We used a stochastic mathematical model informed by South African data to simulate one year of sexual behavior of a female cohort (average 1.2 sex-days/week) under three PrEP regimens from the trial: daily (DD), time-driven (TDD, two regular pills/week 3-4 days apart plus one pill within 2h after sex) and event-driven (EDD, pills taken within 2 days before and 2h after sex) dosing. We explored a wide range of PrEP efficacy per sex act defined as fully covered if pills were taken within 2 days before and 1 day after an act and partially covered if only one of these pills were taken. Regimen effectiveness was estimated as 1 minus the ratio of HIV incidence when PrEP is used vs not used. As a proxy for costs saved, the number of pills required for each regimen was compared across different frequencies and distribution of sexual intercourse assuming perfect adherence.

Poster Abstracts

Results: Data from the South African site suggest that 72% (21%), 36% (53%) and 42% (46%) of sex acts were fully (partially) covered with DD, TDD and EDD, respectively. At reported coverage, predicted PrEP effectiveness was 39%, 18%, 21%with DD, TDD and EDD, respectively, assuming 70% PrEP efficacy only for fully covered sex acts (see Figure). Regimens’ effectiveness increased to 47% (DD), 33% (TDD) and 35% (EDD) assuming 35% PrEP efficacy for partially covered sex acts. Assuming perfect adherence, 2, 3-4, and 4-5 pills/week are required with EDD for 1, 2 and 3 sex-days/week, respectively compared to 2-3, 2-4 or 3-5 pills/week with TDD and 7 pills/week for DD. Fewer pills are needed with EDD if sex-days are successive and with TDD if sex-days coincide with regular pill-taking days. Conclusions: Non-daily PrEP may substantially reduce the number of pills required for the level of sexual activity observed in the HPTN 067 ADAPT trial. However, non-daily PrEP is unlikely to be as effective as daily PrEP in reducing HIV incidence among women in South Africa due to higher sex act coverage observed in the daily use arm. The significant proportion of sex acts partially covered by PrEP implies that the effectiveness of non-daily PrEP depends on the protection provided with partial dosing.

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CROI 2016