CROI 2020 Abstract eBook

Abstract eBook

Poster Abstracts

965 THE RATIONALE FOR A 3-TEST HIV DIAGNOSTIC ALGORITHM: BALANCING ACCURACY AND COST Jeffrey Eaton 1 , Anita Sands 2 , Magdalena Barr-Dichiara 2 , Muhammad S. Jamil 2 , Thokozani Kalua 3 , Andreas Jahn 3 , Rachel Baggaley 2 , Cheryl Johnson 2 1 Imperial College London, London, UK, 2 WHO, Geneva, Switzerland, 3 Malawi Department of HIV and AIDS, Lilongwe, Malawi Background: To ensure >99% positive predictive value (PPV) for HIV testing strategies (HTS) in all settings, WHO 2015 Guidelines recommended two consecutive reactive HIV tests to diagnose HIV infection in high-prevalence (>5%) and three consecutive reactive tests in low-prevalence (≤5%) settings. As awareness of HIV status and treatment coverage reaches high levels, positivity among HTS clients is now below 5% even in high HIV prevalence settings. Consequently, countries employing the ‘high-prevalence’ strategy should consider if, when, and how to transition to a strategy with three-assays for HIV diagnosis. We estimated the HIV testing outcomes, commodities required, and incremental cost for the 3-test versus 2-test strategy. Methods: We created a probability model to simulate HIV testing outcomes of the high- and low-prevalence strategies recommended in WHO 2015 HTS Guidelines, including recommended repetition of discrepant assays. We assumed each assay in the algorithm had 99% sensitivity and 98% specificity, minimum thresholds required to obtain WHO prequalification. Fully loaded costs indicative of a low/middle-income setting were US$2 per client plus commodity costs of $1.30, $2.30, and $2.50 per A1, A2, and A3 assay used, respectively. We calculated expected HIV testing outcomes per 100,000 persons tested with positivity ranging from 0.1% to 20%: expected number of false- positive and false-negative misclassifications, positive and negative predictive value, number of each assay used, and total cost. Results: The expected number of false-positive misclassifications reduced from around 45 to fewer than 1 per 100,000 tested for the 3-test strategy at all positivity levels (Table 1). The PPV of the testing strategy was well above the 99% target at all positivity levels for the 3-test strategy. The number of A1 and A2 assays utilized did not change; the number of A3 assays required was expectedly greater with the 3-test strategy but still much lower than the number of A2 required. The total cost of the 3-test strategy was only 2.5% greater than the 2-test strategy at 5% positivity, reflecting that HTS cost programme cost is primarily determined by the number of A1 conducted. Conclusion: The 3-test strategy ensured high PPV at all HIV positivity levels for a modest incremental cost relative to the 2-test strategy. In light of low positivity, we suggest all countries transition to a unified strategy with three reactive tests for HIV diagnosis in accordance with latest WHO guidance released in 2019.

964 DOES PROVISION OF FREE HIV SELF-TESTING KITS INCREASE HIV DIAGNOSIS IN MSM?

Alison Rodger 1 , Leanne McCabe 1 , Andrew N. Phillips 1 , Fiona Lampe 1 , Fiona M. Burns 1 , Denise Ward 1 , Valerie Delpech 2 , Peter Kirwan 2 , Peter Weatherburn 3 , T Charles Witzel 3 , Roger Pebody 4 , Roy Trevelion 5 , Yolanda Collaco-Moraes 1 , Sheena McCormack 1 , David Dunn 1 1 University College London, London, UK, 2 Public Health England, London, UK, 3 London School of Hygiene & Tropical Medicine, London, UK, 4 NAM Publications, London, UK, 5 HIV i-Base, London, UK Background: High levels of HIV testing in men who have sex with men (MSM) remain key to reducing incidence, particularly in men who have condomless anal intercourse (CAI) with multiple partners. There is little evidence about the effectiveness of free HIV self-testing (HIVST) to increase HIV diagnosis rates in MSM. We aimed to assess if the offer of a single free HIVST kit led to increased diagnosis of HIV infections that linked to care. Methods: SELPHI is an internet based, open-label, randomized controlled that used online advertising to recruit men potentially interested in HIVST. Enrolment criteria were male (including trans), aged ≥16 years, ever had anal intercourse (AI) with a man, not known to be HIV positive and consent to link to national HIV surveillance databases (to ascertain new HIV diagnoses and linkage to care). Participants were randomly allocated 3:2 at enrolment to a free HIVST (Baseline Test [BT]) versus no free HIVST (no Baseline Test [nBT]). Online surveys collected data at baseline, 2 weeks (2w) (BT only) and 3 months (3m) post- enrolment. Men in BT were asked about HIVST use and linkage to care if reactive. Primary outcome was a confirmed new HIV diagnosis within 3m of enrolment. Results: 10,111 men were randomized (6049 BT; 4062 nBT); median age 33 years (IQR 26-44); 89%white; 20% born outside UK; 0.8% trans men; 47% degree educated; 15% never HIV tested; 8% ever and 4% currently on PrEP. At enrolment 89% reported AI and 72% CAI with ≥1 male partner in previous 3m. 4194/4695 (89%) in BT reported using the HIVST kit. No significant difference at 3m in confirmed new HIV diagnoses (primary outcome)(p=0.64, 19 [0.3%] in BT vs 15 [0.4%] in nBT). Men randomized to BT were more likely to HIV test in 3m after enrolment (96% vs 42%; risk ratio 2.27 95%CI 2.13, 2.40), but a higher proportion in nBT tested for HIV in the 3m after enrolment (42%) compared to 3m before (21%). STI testing rates between arms were similar (22% BT vs 25% nBT). Conclusion: Reflecting national declines in MSM, new HIV diagnoses were low in both arms by 3 months after enrolment, with no significant difference between men randomized to receive an HIVST kit (BT) and those who were not (nBT). Men randomized to nBT may have been motivated to HIV test through other routes in the 3 months after enrolment. However, HIV testing rates were overall higher in the 3 months after enrolment in those offered HIVST, with similar rates of STI screening.

Poster Abstracts

966 FALSE-POSITIVE 4TH GENERATION HIV TEST RESULTS IN THE EMERGENCY DEPARTMENT

Gabriel A. Wagner 1 , Ryan Anson 2 , Nicole Gamache-Kocol 3 , Kushagra Mathur 1 , Megan Lo 1 , Jeffrey H. Burack 3 , Annette Shaieb 3 , Jill Blumenthal 1 , Susan J. Little 1 , Martin Hoenigl 1

CROI 2020 362