Switching from first-line ART with suppressed viral load linked to treatment failure

People who switch away from their initial antiretroviral therapy (ART) regimen when their viral load is undetectable may have a higher likelihood of subsequent virological failure, researchers reported at the 20th International AIDS Conference last week in Melbourne. However, the association varied across groups and the researchers suggested their findings may reflect issues such as adherence or treatment changes due to pregnancy.

Experts recommend starting HIV treatment with a maximally potent combination antiretroviral regimen, especially for people with high viral load. But even in the modern ART era many people wish to switch regimens for the sake of better tolerability or simplicity. Prior studies indicate that about 40% of patients modify their first regimen.

Marina Klein of McGill University in Montreal and colleagues evaluated why people switch first-line regimens for reasons other than inadequate viral suppression – for example, to reduce side-effects or improve convenience – and the link between switching and subsequent virologic failure. Suppressed viral load was defined as two HIV RNA measurements below 50 copies/ml at least one month apart; virological failure was defined as viral load above 1000 copies/ml.

This analysis looked at 2807 previously untreated people with HIV in the multi-site Canadian CANOC cohort who started combination ART between 2005 and 2012. Most (87%) were men and the median age was 42 years. The median baseline CD4 T-cell count was 260 cells/mm3, 12% had a history of injecting drug use and 15% were coinfected with hepatitis C virus (HCV).

Liz Highleyman
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