CROI 2017 Abstract e-Book

Abstract eBook

Poster and Themed Discussion Abstracts

1026 ANALYZING “MISSING MEN” IN THE UK HETEROSEXUAL HIV EPIDEMIC BY DSPS-HIV SIMULATIONS Emma B. Hodcroft 1 , Manon Ragonnet-Cronin 2 , Joel O. Wertheim 3 , Samantha Lycett 4 , Sergei L. Kosakovsky Pond 5 , Andrew Leigh Brown 6 1 Univ of Edinburgh, Edinburgh, Scotland, 2 Univ of Edinburgh, Midlothian, Scotland, 3 Univ of California San Diego, San Diego , CA, 3 Temple Univ, Philadelphia, PA, USA Background: In the UK heterosexual HIV epidemic, there are six times as many clusters containing only women as containing only men. The abundance of female-only clusters implies a set of ‘missing men’ in currently available transmission networks, perhaps because these men are diagnosed later in infection, are not recruited to care, and/or are responsible for multiple onward transmissions. To investigate factors responsible for the excess of female-only clusters, we conducted a simulation to approximate the UK HIV epidemic, using the Discrete Spatial Phylo Simulator HIV (DSPS-HIV). In parallel, network analysis was undertaken on sequences from the UK HIV Drug Resistance Database (UK RDB) to identify characteristics of female-dominated and female-only clusters. Methods: DSPS-HIV is an individual-based stochastic epidemic simulator that produces realistic viral phylogenies and sequences, allowing analysis of simulated data using the same methods as used on real data. We (i) allowed men to transmit at twice the rate of women, and (ii) delayed sampling in heterosexual men by approx. 6 months, while sampling heterosexual women approx. 6 months earlier. These effects were explored singly and jointly. Analysis of sequence data from UK RDB was with BEAST and the R package ‘Network.’ Results: In baseline simulations, we found a mean ratio of 1.7 female-only to male-only clusters [FMC] due to women’s risk from contact with bisexual men. Introducing gender- dependent transmission alone into the DSPS-HIV simulations elevated the mean FMC ratio to 3.0, and with delayed/early sampling it was 2.2. Combining the effects together yielded the FMC ratio of 4.4 (Table 1). Network analysis of UK RDB sequences showed that men have a mean degree of 1.9 (max=44) compared to 1.5 (max=27) for women. Identifying the nearest sequence to female-only clusters showed no significant difference in diagnosis date compared to the cluster. Conclusion: Here we show the utility of simulations to investigate causal factors in real-world data. Both simulations and network analysis showed that the increased risk of male- to-female transmission plays an important role in the excess of female-only clusters. In combination with delayed/early sampling, we came close to recapitulating the observed FMC ratio, implying that sampling delays may also partially explain ‘missing men.’ Further work on the UK RDB and the DSPS-HIV will investigate subtype-specific differences in FMC, as subtypes represent different ethnic and risk groups in the UK. 1027 TEMPORAL EVOLUTION OF HIV SERODISCORDANCY AMONG STABLE COUPLES IN SUB-SAHARAN AFRICA Susanne Awad, Hiam Chemaitelly, Laith J. Abu-Raddad Weill Cornell Med Coll in Qatar, Doha, Qatar Background: The objective of this study was to examine the temporal evolution of HIV sero-discordancy in six representative countries in sub-Saharan Africa (SSA) at different HIV epidemic scales. Historical (1980-2014) trends of seven sero-discordancy measures were assessed as the HIV epidemic emerged, peaked, and saturated. Future temporal evolution (2015-2030) of these measures was also assessed as antiretroviral therapy (ART) is scaled up and the HIV epidemic declines over the coming decades. Methods: A pair-based deterministic mathematical model was constructed to describe HIV transmission dynamics in SSA. The model accommodated for different forms of sexual partnerships and infection statuses. Using nationally-representative epidemiological and demographic input data, trends of sero-discordancy were assessed in six countries at different HIV prevalence scales (low, intermediate, and high). Results: Table 1 shows the definitions of these discordancy measures and their estimated values. In the emerging phase of the HIV epidemics, 54%-93% of couples affected by HIV were discordant. The proportion declined to 45%-88% at epidemic peak and stabilized during the saturated phase. The largest reduction was in high HIV prevalence countries. As the epidemics decline with future ART scale-up, the proportion of discordant couples among HIV affected couples is projected to increase to 70%-92% by 2030. The proportion of discordant couples among all couples increased as the epidemics emerged and peaked at 2%-20% as the epidemics peaked. As the epidemics saturated, this proportion declined following the decline in HIV prevalence. As the epidemics decline further in the future with ART scale-up, it is projected that 0.3%-16% of couples in the population will be discordant by 2030. Results on other discordancy measures can be found in Table 1. Conclusion: Regardless of HIV epidemic scale across countries, HIV sero-discordancy varied with the evolution of the epidemic. However, the degree of variation depended on HIV epidemic scale. The largest variations in discordancy were observed in high HIV prevalence countries. Discordancy was projected to increase in most countries as the epidemic continues its decline with ART scale-up. These findings inform strategic planning and resource allocation for HIV intervention programming among discordant couples. 1028 EFFECTIVENESS AND COST-EFFECTIVENESS OF HIV SCREENING STRATEGIES ACROSS EUROPE Guillaume Mabileau 1 , Julia Del Amo 2 , Kristi Rüütel 3 , A. David Paltiel 4 , Liis Lemsalu 3 , Asunción Díaz 2 , Jesús Martín Fernández 5 , Rochelle P. Walensky 6 , Kenneth Freedberg 6 , Yazdan Yazdanpanah 1 1 INSERM, Paris, France, 2 Inst of Hlth Carlos III, Madrid, Spain, 3 Natl Inst for Hlth Development, Tallinn, Estonia, 4 Yale SPH, New Haven, CT, USA, 5 Univ Rey Juan Carlos, Madrid, Spain, 6 Massachusetts General Hosp, Boston, MA, USA Background: In the eras of both Treatment as Prevention and PrEP, HIV testing has become critical to control the epidemic. We evaluated the clinical impact, costs, and cost- effectiveness of different testing strategies for both high-risk individuals and the general population in three European countries with different epidemic profiles. Methods: We used a mathematical model of HIV disease, the Cost-Effectiveness of Preventing AIDS Complications (or “CEPAC”) Model, with country-specific clinical & economic data to project discounted life expectancy, cost and incremental cost-effectiveness ratios (ICERs) of alternative HIV screening strategies in France, Spain, and Estonia. We compared these strategies to current HIV testing practices in adults aged 18-69 in the overall population, and among Men who have Sex with Men (MSM), and People Who Inject Drugs (PWID). Input data by country included (Estonia/France/Spain): HIV prevalence (Overall: 1.3%/0.4%/0.4%; MSM: 4%/17%/6%; PWID: 55%/18%/33%), incidence per 100py (Overall: 0.03/0.02/0.01; MSM: 1.0/1.0/0.6; PWID: 6.0/0.1/1.5), mean CD4 at ART initiation (Table), current screening performance including acceptance and linkage-to-care rates; and costs for ART, HIV tests, and HIV care. We labeled a strategy “cost-effective” if its ICER in 2015€ per year of life saved (YLS) was less than the annual per capita GDP of the country (20,000€/29,000€/24,300€). Results: Frequent HIV testing among high-risk groups increased life expectancy in people living with HIV (PLWH) (Table). Among MSM, one test every 12 months in Estonia and France, and every 3 years in Spain, had an ICER of 16,200; 23,900; and 25,400€/ YLS. Among PWID, testing every month in Estonia, every 3 years in France, and every 6 months in Spain had ICERs of 11,000; 27,700; and 18,300€/YLS, respectively. In the general population, one additional lifetime test in France and Spain, and testing every 3 years in Estonia had ICERs of 37,100; 28,100; and 13,000€/YLS. Our findings were most sensitive to uncertainty in rates of HIV incidence, the screening frequency, and costs of HIV tests and ART. Conclusion: In France and Estonia, MSM should be tested every 12 months; and in Spain every 36 months. In Spain and France, PWID should be tested every 6 and 36 months, while in Estonia, the frequency could be even higher. HIV testing in the general population has also proven to be cost-effective. For optimal value, HIV screening strategies in Europe should be tailored to each country’s epidemic.

Poster and Themed Discussion Abstracts

CROI 2017 443