CROI 2018 Abstract eBook

Abstract eBook

Poster Abstracts

924 AN AGE-STRATIFIED RISK SCORE TO PREDICT HIV ACQUISITION IN YOUNG SOUTH AFRICAN WOMEN Emma K. Burgess 1 , Nonhlanhla Yende-Zuma 2 , Delivette Castor 1 , Quarraisha Abdool Karim 2 1 United States Agency for International Development, Washington, DC, USA, 2 CAPRISA, Durban, South Africa Background: Prioritizing high-risk women in HIV hyperepidemic settings is important for optimized introduction and scale of new prevention methods (e.g., oral PrEP). We assessed the performance of a risk score derived from the VOICE cohort using the CAPRISA 004 dataset and modified the score for age- specific prediction. Methods: The initial risk score (IRS) included 7 items: age; HSV-2 serostatus; partner exclusivity; marital/co-habitation; partner’s financial support; alcohol use, and STIs. We developed an age-stratified modified risk score (MRS) and public health use risk score [(PHRS) excludes non-routine HSV serotesting] and evaluated risk prediction according to the area under the curve (AUC), sensitivity, specificity, and un/adjusted hazard ratios (aHR). Given the effect of the tenofovir gel, only participants in the CAPRISA 004 placebo arm (n=444) were used in this analysis. Results: There were 60 HIV infections over 660.7 person-years of follow-up (incidence=9.08/100 person-years (PY); 95%CI 7.05, 11.7). Women with IRS scores of <8 had a significantly lower HIV incidence of 5.95/100 PY (95%CI 3.88, 9.12) compared to those with scores ≥8 (12.83/100 PY; 95%CI 9.29, 17.7). This cut-off had a sensitivity of 64% and specificity of 57% (Figure 1). The AUC was 0.66. Among the 7 IRS items, only 3 were significantly associated with HIV acquisition in this dataset; age <25 years (aHR=2.47; 95%CI 1.24, 4.89), responding “don’t know” and “yes” that your partner has other partners (aHR=4.02; 95%CI 1.22, 13.3 and 3.77; 95%CI 1.07, 13.3), and being HSV-2 positive (aHR=2.10; 95%CI 1.19, 3.68). The age stratified MRS showed the most predictive score for women <25 years included HSV-2, casual partnerships and partner exclusivity (AUC: 0.70). The PHRS had an AUC of 0.62, and women <25 years with scores <3 vs. ≥3 had incidences of 1.57 (95%CI 0.22, 11.16) and 12.6/ 100 PY (95%CI 9.17, 16.44), respectively. Conclusion: The ability of the IRS to predict incident HIV infections was comparable to previous validations. However, a cut-off where women were at a substantially low risk of HIV infection could not be determined. Exploratory analyses show the MRS and PHRS to be simpler tools that can be used for PrEP counselling, increasing risk perception and to focus interventions on modifiable risk factors. Yet, relatively lower risk women still had high HIV incidence suggesting further modification to the tool or the need to offer PrEP to any at-risk young woman in hyperepidemic settings.

Background: Serosorting can have potential benefits including reduction in HIV incidence and better ART adherence and retention. Although serosorting behavior has been reported among high risks groups such as men who have sex with men, its role is largely unknown in heterosexual couples in a high HIV endemic setting in sub-Saharan Africa. Methods: Data from a population-based open cohort between January 2003 and December 2016 in KwaZulu-Natal, South Africa was used. Individuals with known HIV status, not currently in stable conjugal relationship (CR), were included for the analysis. Competing-risks survival regression was used to estimate the incidence of conjugal relationship formation with known HIV seropositive partners by participants’ HIV status, where formation with known seronegative or unknown serostatus partners was fitted as the competing risks. HIV status was used as a time-varying exposure. Hazard ratios (HR) and 95% confidence intervals (CI) are reported. Results: A total of 24,232 HIV-negative and 10,384 HIV-positive individuals including 3,345 who seroconverted were followed over 166,686 person-years (PY) follow-up time. We observed 68 (0.4 per 1000 PY) CR formation with known HIV seropositive, 193 (1.2/1000 PY) with known seronegative and 385 (2.3/1000 PY) with unknown serostatus partners. The average median age at the time of CR formation was 27 (IQR:21-36). HIV-positive individuals had 2.17 (95% CI: 1.29-3.64) times higher hazard of CR formation with a HIV-positive partner, compared to HIV-negative individuals. The adjusted HR was 2.26 (95% CI: 1.29-3.96) after adjusting for age, sex, education, household asset, and the number of partners in the past 12 months. When stratified by participants’ age at <30 vs. 30+ years, the association became only significant in those aged 30+ years (HR=4.11; 95% CI: 1.93-8.73). Conclusion: Positive serosorting was observed among HIV-positive individuals in older heterosexual couples in rural KwaZulu-Natal, South Africa. Such behavior might be due to increased knowledge for HIV and access to antiretroviral therapy (ART) care and may lead to better long-term health outcomes. 926 SELF-REPORTED RISKY SEXUAL PRACTICES AMONG ADOLESCENTS AND YOUNG ADULTS IN BOTSWANA Unoda A. Chakalisa 1 , Kathleen Wirth 2 , Kara Bennett 3 , Etienne Kadima 1 , Kutlo Manyake 1 , Tendani Gaolathe 1 , Pamela J. Bachanas 4 , Tafireyi Marukutira 5 , Scott Dryden-Peterson 6 , Mompati O. Mmalane 1 , Joseph Makhema 1 , Molly Pretorius Holme 2 , Max Essex 2 , Shahin Lockman 6 , Kathleen M. Powis 7 1 Botswana Harvard AIDS Inst Partnership, Gaborone, Botswana, 2 Harvard University, Cambridge, MA, USA, 3 Bennett Statistical Consulting, Inc, New York, NY, USA, 4 CDC, Atlanta, GA, USA, 5 Monash University, Melbourne, VIC, Australia, 6 Brigham and Women’s Hospital, Boston, MA, USA, 7 Massachusetts General Hospital, Boston, MA, USA Background: An estimated 1700 adolescent and young adults (15-24) acquire HIV daily, accounting for over a third of new HIV cases. Understanding sexual practices of this high-risk group is critical in designing HIV prevention programming. Methods: We sought to examine the sexual practices, regardless of HIV status, of adolescents and young adults aged 16-24 years participating in the Botswana Combination Prevention Project (BCPP), an ongoing pair-matched, cluster-randomised trial of 30 communities. Information on age of sexual debut, number of sexual partners, condom and alcohol use during sex, intergenerational sex (intercourse with a partner 10 or more years older), and transactional sex (receiving money, transport, food, drink or other goods in exchange for sex) were collected at enrollment. Modified Poisson estimating equations were used to obtain prevalence ratios comparing engagement in different sexual practices according to gender, adjusting for community-level clustering. Results: Among the 12,610 BCPP participants, 3,380 were 16-24 years-of- age. Of these 2,311 (68%) reported being sexually active with significantly more females reporting ever being sexually active compared with males (65% vs 35% respectively; p<0.0001). Sexually active individuals reported significantly higher levels of poverty, indicated by lack of television (44.2% vs 37.5%; p=0.0004) or refrigeration (56% vs 46%; p<0.0001), and reliance on a communal stand pipe for water (26% vs 20%; p<0.0001). Compared to males, sexually active females were significantly more likely to report inconsistent condom use (PR: 1.61; 95% CI: 1.44-1.80), intergenerational sex (PR: 9.00; 95% CI 5.84-13.88), and transactional sex (PR: 3.46; 95% CI 2.07-5.77). [Table 1] In contrast, women were significantly less likely to engage in sex before age 15

Poster Abstracts

925 SEROSORTING FOR CONJUGAL RELATIONSHIP FORMATION IN HETEROSEXUAL COUPLES, SOUTH AFRICA Hae-Young Kim 1 , Alain Vandormael 1 , Andrew Tomita 1 , Till Bärnighausen 2 , Frank Tanser 1 1 Africa Health Research Institute, Mtubatuba, South Africa, 2 Heidelberg University, Heidelberg, Germany

CROI 2018 353