Abstract
Mortality assessment in cohorts with high numbers of persons lost to follow-up (LTFU) is challenging in settings with limited civil registration systems. We aimed to assess mortality in a clinical cohort (the Kilombero and Ulanga Antiretroviral Cohort (KIULARCO)) of human immunodeficiency virus (HIV)-infected persons in rural Tanzania, accounting for unseen deaths among participants LTFU. We included adults enrolled in 2005-2015 and traced a nonrandom sample of those LTFU. We estimated mortality using Kaplan-Meier methods 1) with routinely captured data (method A), 2) crudely incorporating tracing data (method B), 3) weighting using tracing data to crudely correct for unobserved deaths among participants LTFU (method C), and 4) weighting using tracing data accounting for participant characteristics (method D). We investigated associated factors using proportional hazards models. Among 7,460 adults, 646 (9%) died, 883 (12%) transferred to other clinics, and 2,911 (39%) were LTFU. Of 2,010 (69%) traced participants, 325 (16%) were found: 131 (40%) had died and 130 (40%) had transferred. Five-year mortality estimates derived using the 4 methods were 13.1% (A), 16.2% (B), 36.8% (C), and 35.1% (D), respectively. Higher mortality was associated with male sex, referral as a hospital inpatient, living close to the index clinic, lower body mass index, more advanced World Health Organization HIV clinical stage, lower CD4 cell count, and less time since initiation of antiretroviral therapy. Adjusting for unseen deaths among participants LTFU approximately doubled the 5-year mortality estimates. Our approach is applicable to other cohort studies adopting targeted tracing.