Loss to follow-up correction increased mortality estimates in HIV–positive people on antiretroviral therapy in Mozambique

Abstract

ObjectivesPeople living with human immunodeficiency virus (HIV) on antiretroviral therapy (ART) may be lost to follow-up (LTFU), which hampers the assessment of outcomes. We estimated mortality for patients starting ART in a rural region in sub-Saharan Africa and examined risk factors for death, correcting for LTFU. Study Design and SettingWe analyzed data from Ancuabe, Mozambique, where patients LTFU are traced by phone and home visits. We used cumulative incidence functions to estimate mortality and LTFU. To correct for LTFU, we revised outcomes based on tracing data using different inverse probability weights (maximum likelihood, Ridge regression, or Bayesian model averaging). We fitted competing risk models to identify risk factors for death and LTFU. ResultsThe analyses included 4,492 patients; during 8,152 person-years of follow-up, 486 patients died, 2,375 were LTFU, 752 were traced, and 603 were found. At 4 years after starting ART, observed mortality was 11.9% (95% confidence interval [CI]: 10.9–13.0), but 23.5% (95% CI: 19.8–28.0), 21.6% (95% CI: 18.7–25.0), and 23.3% (95% CI: 19.7–27.6) after correction with maximum likelihood, Ridge regression, and Bayesian model averaging weights, respectively. The risk factors for death included male sex, lower CD4 cell counts, and more advanced clinical stage. ConclusionIn ART programs with substantial LTFU, mortality estimates need to take LTFU into account.