2.2. Testing strategies modeled

We modeled comparative clinical and cost-effectiveness outcomes of no PDR testing, PDR testing with OLA, and PDR testing with CS for women who do not initiate dolutegravir-based first-line ART, over a 15-year time horizon starting in 2019 (t₀). All individuals diagnosed with HIV, regardless of CD4 cell count, are eligible to initiate ART. In the no PDR testing strategy, efavirenz-based ART is empirically given as the first-line regimen to women who avoid dolutegravir due to safety concerns. In the PDR testing strategies using either OLA or CS, patients initiate ART after test results become available, which we assume occurs within one month [19,22]. PI-based ART is initiated for women in whom PDR is detected, and efavirenz-based ART is used for all other women avoiding dolutegravir. We assume an OLA that tests for mutations K103N, M184V, Y181C, and G190A will detect 80% of PDR cases (diagnostic sensitivity = 80%; see Appendix Section 2E for definition of diagnostic vs. analytical sensitivity). Although a meta-analysis found that only 59% of PDR cases in low- and middle-income countries had at least one mutation detectable by OLA [11], a recent trial found that among subjects with virologic failure at 12 months, 100% of subjects with PDR detected by CS were also detected by OLA [18]. Thus, our assumption that OLA PDR testing has a diagnostic sensitivity of 80% is intended to synthesize data from these two studies. We assume CS PDR testing has diagnostic sensitivity of 100%. We assume OLA and CS testing cost $30 and $125 (Maxwel Majiwa, Ph.D., from Kenya Medical Research Institute, personal communication, 29 March 2019) per test, respectively [19]. For all strategies, initial viral load (VL) testing is performed 6 months after ART initiation and is subsequently performed at 12-month intervals.