Abstract Background Pre-exposure prophylaxis (PrEP) is highly effective for HIV prevention. However, breakthrough infections can occur, even with optimal adherence. We evaluated the performance of prospective HIV RNA screening in cisgender men and transgender women who have sex with men using long-acting injectable cabotegravir (CAB-LA) pre-exposure prophylaxis (PrEP) in HPTN 083. Methods In the Open Label Extension of HPTN 083, sites performed HIV rapid, antigen/antibody (Ag/Ab) and RNA testing at each visit. Results from site testing and retrospective HIV testing were used to determine final HIV status and identify the first HIV positive visit. Results HIV RNA screening was associated with fewer diagnostic delays (7% vs. 47% of cases, p=0.02) and earlier treatment initiation (median 15 vs. 62 days, p=0.02). Drug resistance was less frequent with RNA screening (15% vs. 31% of cases, p=0.22). Five cases were first detected with RNA testing only. Sensitivity and specificity of RNA testing were 93% (95% CI: 76, 99) and 99.92% (95% CI: 99.88, 99.95), respectively. However, positive predictive value (PPV) was low overall (55%; 95% CI: 40, 69) and was lower if CAB-LA was administered 6 months earlier (29%; 95% CI: 13, 49). Some false positive RNA test results led to delay or discontinuation of CAB-LA injections. Conclusions HIV RNA screening improved clinical outcomes in the setting of CAB-LA PrEP, but the PPV for RNA screening was low which could compromise patient care.
Landovitz et al. (Fri,) studied this question.