Non-adherence to ART — and not pretreatment drug-resistant mutations — explain the “vast majority” of elevated viral load episodes in women initiating ART during pregnancy, according to results from a study conducted in South Africa.
“Globally, we know that HIV-infected women who are on ART experience elevated HIV viral load during pregnancy and during the postpartum period. This has been well-demonstrated in different parts of sub-Saharan Africa in particular, including in South Africa,” Landon Myer, PhD, MD, who leads the school of public health at the University of Cape Town in South Africa, told Infectious Disease News.
“But there are not very good data on what is causing the elevated viral load despite these women being on ART. Is it pretreatment ART drug resistance, about which there is growing concern, or simply that women are not adhering to treatment as well during pregnancy or postpartum? That is the basic question we set out to answer.”
Using a cohort of women who initiated ART during pregnancy, Myer and colleagues compared 80 women who had an elevated viral load after initial suppression with 87 matched women who maintained suppression over time to evaluate pre-ART drug resistant mutations.
Results showed that the prevalence of pre-ART drug-resistant mutations was 10% in cases and 5% in controls (adjusted OR = 1.53; 95% CI = 0.40-5.86). According to researchers, all mutations were to non-nucleoside reverse transcriptase inhibitors (NNRTIs), and at the time of elevated viral load, 19% of cases had antiretrovirals detected in plasma, compared with 87% of controls who were suppressed at a matched time point (aOR = 131.43; 95% CI = 32.75-527.40). The researchers estimated that less than 10% of all elevated viral load in the cohort was attributable to pre-ART drug resistant mutations compared with the more than 90% that were attributable to ART nonadherence.
“We are all very concerned with ART drug resistance and were surprised to find that it was only weakly associated with elevated viral load on ART in this patient population; at a population level, it appears to account for only a very small fraction of cases with elevated viral load,” Myer said.
“Instead, we found that nonadherence to ART appeared to explain the vast majority of episodes of elevated viral load. This is important for thinking about the future of ART for this patient population in South Africa and other countries that are moving away from efavirenz (an NNRTI) to use dolutegravir (an integrase inhibitor) as a first-line ART, in part due to concerns about NNRTI resistance, as it’s not clear that the challenges of ART adherence will be any different with dolutegravir.”
By Caitlyn Stulpin