Early outcomes and the virological effect of delayed treatment switching to second-line therapy in an antiretroviral roll-out programme in South Africa

Background: More patients in resource-limited settings are starting second-line antiretroviral treatment (ART) following first-line ART failure. We aimed to describe predictors of lack of virological suppression in HIV-infected patients on second-line ART in a roll-out programme in South Africa.

Methods: A retrospective analysis was performed on an adult HIV treatment cohort who started second-line ART (lopinavir/ritonavir, didanosine and zidovudine) after virological failure of first-line ART (two consecutive HIV RNA>1,000 copies/ml). Predictors of week 24 lack of suppression (HIV RNA>400 copies/ml) on second-line ART were determined by bivariate analysis where missing equals failure. A multivariable model that adjusted for gender, age and time to ART switch was used. We tested these findings in sensitivity analyses defining lack of suppression at week 24 as HIV RNA>1,000 and >5,000 copies/ml.

Results: Of 6,339 patients on ART, 202 started second-line ART. At week 24, an estimated 41% (95% CI 34-47) did not achieve virological suppression. Female sex (adjusted OR 2.25, 95% CI 1.03-4.88) and time to ART switch (adjusted OR 1.07, 95% CI 1.01-1.14 for each additional month) increased the risk of lack of virological suppression. Age, CD4(+) T-cell count and HIV RNA at second-line ART initiation did not predict this outcome. In multivariate models, these findings were insensitive to the definition of lack of virological suppression.

Conclusions: A substantial number of HIV-infected patients do not achieve virological suppression by week 24 of second-line ART. Women and patients with delayed start of second-line ART after first-line ART failure were at an increased risk of lack of virological suppression.