Background: Currently, boosted protease inhibitor-containing regimens are the only option after first-line regimen failure available for patients in most resource-limited settings, yet little is known about long-term adherence and outcomes.
Methods: We enrolled patients with virologic failure (VF) who initiated lopinavir/ritonavir-containing second-line antiretroviral therapy (ART). Medication possession ratios were calculated using pharmacy refill dates. Factors associated with 12-month second-line virologic suppression [viral load (VL) <50 copies/mL] and adherence were determined.
Results: One hundred six patients (median CD4 count and VL at failure: 153 cells/mm(3) and 28,548 copies/mL, respectively) were enrolled. Adherence improved after second-line ART switch (median adherence 6 months prior, 67%; median adherence during initial 6 months of second-line ART, 100%; P = 0.001). Higher levels of adherence during second-line ART was associated with virologic suppression at month 12 of ART (odds ratio 2.5 per 10% adherence increase, 95% CI 1.3 to 4.8, P = 0.01). Time to virologic suppression was most rapid among patients with 91%-100% adherence compared with patients with 80%-90% and <80% adherence (log rank test, P = 0.01). VF during 24 months of second-line ART was moderate (month 12: 25%, n = 32/126; month 18: 21%, n = 23/112; and month 24: 25%, n = 25/99).
Conclusions: The switch to second-line ART in South Africa was associated with an improvement in adherence, however, a moderate ongoing rate of VF--among approximately 25% of patients receiving second-line ART patients at each follow-up interval--was a cause for concern. Adherence level was associated with second-line ART virologic outcome, helping explain why some patients achieved virologic suppression after switch and others did not.