Despite expanding viral load (VL) testing to resource-limited settings, resistance testing is unavailable. Understanding drug resistance patterns is essential to devise treatment switch algorithms. We evaluated reverse-transcriptase (RT) inhibitor resistance among a previously unmonitored antiretroviral therapy (ART) cohort in Malawi.
We enrolled HIV-infected persons at ART clinics in Malawi (03/2013-01/2014). Blood was collected via fingerstick dried blood spot (DBS) cards. We used an in-house nested RT-PCR for two regions of the RT gene from DBS-extracted nucleic acid, followed by population sequencing for persons on 1st-line ART experiencing virological failure (≥5000 copies/ml) with confirmatory testing to determine resupression (<1000 copies/ml). Resistance was evaluated using Stanford University HIV Drug Resistance Database.
Among 1,498 enrolled patients, 1,348 (90.3%) were on ART >12 months; 161 (10.8%) had signs of clinical failure. 88 (5.8%) had VL >5,000 copies/ml, 80 of whom were on ART >12 months and 16 with signs of clinical failure. After adherence counseling, 78/88 (88.6%) had confirmatory specimens collected; 13/78 (16.7%) resupressed (<1000 copies/ml). There was no difference in likelihood of resuppression comparing persons on ART <12 vs >12 months (16.4% vs 20%, p=0.8), and a trend towards greater resuppression among those with clinical symptoms (37.5% vs 14%, p=0.1). Among participants with elevated VL, 73/88 (83%) had resistance testing attempted; 57/61 (95%) of amplified sequences demonstrated NRTI (51) and/or NNRTI (55) resistance. There was a trend towards greater resistance among those on ART >12 vs <12 months (95% vs 80%, p=0.2) as well as those with clinical failure vs no clinical failure (100.0% vs 91.5%, p=0.3).
We observed high rates of ART resistance among patients with elevated VLs in a Malawian cohort of previously unmonitored patients. Our observations might suggest a role for immediate switching given low rates of resuppression and high levels of resistance, but further characterization of the population benefit from immediate switch will require additional evaluation.
S. E. Rutstein,
J. Nelson, None
D. Kamwendo, None
R. Mataya, None
W. Miller, None
M. Hosseinipour, None