For patients with HIV, frequent viral load monitoring and pretreatment genotypic resistance testing result in lower levels of drug resistance, even when treatment failure occurs, according to results published in the Journal of Antimicrobial Chemotherapy.

The researchers compared the prevalence of different resistance mutations among a cohort with regular routine viral load monitoring (Switzerland) and cohorts with limited access to viral load testing (Uganda and Lesotho).

The study included participants with HIV who had genotypic resistance testing on virologic failure (≥1000 copies/mL) and were receiving antiretroviral therapy consisting of at least 1 nonnucleoside reverse transcriptase inhibitor and 2 nucleoside reverse transcriptase inhibitors.

Participants from Lesotho who had 2 subsequent viral loads ≥1000 copies/mL despite enhanced adherence counseling (n=58) were included. Participants from Uganda who had 1 viral load ≥1000 copies/mL (n=120) were included. Participants from the Swiss HIV Cohort Study who had no history of monotherapy or dual therapy with the first genotypic resistance testing on virologic failure (n=61) were included.

In total, 50.8% of participants from the Swiss HIV Cohort Study, 72.5% from Uganda, and 81.0% from Lesotho had HIV with high-level resistance to at least 2 drugs from their current regimen.

The researchers found that Stanford resistance scores were higher among participants from Uganda compared with Switzerland for all drugs used in first-line treatment except zidovudine and tenofovir (P<.01). Stanford resistance scores were higher among participants from Lesotho compared with Uganda for all drugs used in first-line treatment except zidovudine (P<.01).

“Even though challenges of virological monitoring include costs, complexity and both patient and clinician awareness, our results highlight the importance of further upscaling virological monitoring in resource-limited settings,” concluded the researchers.

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Reference

Bachmann N, von Braun A, Labhardt ND, et al; Swiss HIV Cohort Study. Importance of routine viral load monitoring: higher levels of resistance at ART failure in Uganda and Lesotho compared with Switzerland. [published online November 21, 2018]. J Antimicrob Chemother. doi:10.1093/jac/dky436