To compare outcomes of antiretroviral therapy (ART) in South Africa, where viral load monitoring is routine, with Malawi and Zambia, where monitoring is based on CD4 cell counts.
We included 18,706 adult patients starting ART in South Africa and 80,937 patients starting in Zambia or Malawi. We examined CD4 responses in models for repeated measures, and the probability of switching to second-line regimens, mortality and loss to follow-up in multi-state models, measuring time from six months.
In South Africa 9.8% (9.1-10.5%) had switched at 3 years, 1.3% (95% CI 0.9-1.6%) remained on failing first-line regimens, 9.2% (8.5-9.8%) were lost to follow-up and 4.3% (3.9-4.8%) had died. In Malawi and Zambia more patients were on a failing first-line regimen (3.7%, 3.6-3.9%), fewer patients had switched (2.1%, 2.0-2.3%) and more patients were lost (15.3%, 15.0-15.6%) or had died (6.3%, 6.0-6.5%). Median CD4 cell counts were lower in South Africa at start of ART (93 vs. 132 cells/μL, p < 0.001) but higher after 3 years (425 vs. 383 cells/μL, p < 0.001). The hazard ratio comparing South Africa with Malawi and Zambia, adjusted for age, sex, first-line regimen and CD4 cell count, was 0.58 (95% CI 0.50-0.66) for death and 0.53 (0.48-0.58) for loss to follow-up.
Over 3 years of ART mortality was lower in South Africa than in Malawi or Zambia. The more favourable outcome in South Africa might be explained by viral load monitoring leading to earlier detection of treatment failure, adherence counselling and timelier switching to second-line ART.