Abstract
BackgroundIn sub-Saharan Africa, a large proportion of HIV positive patients on antiretroviral therapy (ART) are lost to follow-up, some of whom are dead. The objective of this study was to validate methods used to correct mortality estimates for loss-to-follow-up using a cohort with complete death ascertainment.MethodsRoutinely collected data from HIV patients initiating first line antiretroviral therapy (ART) at the Infectious Diseases Institute (IDI) (Routine Cohort) was used. Three methods to estimate mortality after initiation were: 1) standard Kaplan-Meier estimation (uncorrected method) that uses passively observed data; 2) double-sampling methods by Frangakis and Rubin (F&R) where deaths obtained from patient tracing studies are given a higher weight than those passively ascertained; 3) Nomogram proposed by Egger et al. Corrected mortality estimates in the Routine Cohort, were compared with the estimates from the IDI research observational cohort (Research Cohort), which was used as the “gold-standard”.ResultsWe included 5,633 patients from the Routine Cohort and 559 from the Research Cohort. Uncorrected mortality estimates (95% confidence interval [1]) in the Routine Cohort at 1, 2 and 3 years were 5.5% (4.9%–6.3%), 6.6% (5.9%–7.5%) and 7.4% (6.5%–8.5%), respectively. The F&R corrected estimates at 1, 2 and 3 years were 11.2% (5.8%–21.2%), 15.8% (9.9%–24.8%) and 18.5% (12.3% –27.2%) respectively. The estimates obtained from the Research Cohort were 15.6% (12.8%–18.9%), 17.5% (14.6%–21.0%) and 19.0% (15.3%–21.9%) at 1, 2 and 3 years respectively. Using the nomogram method in the Routine Cohort, the corrected programme-level mortality estimate in year 1 was 11.9% (8.0%–15.7%).ConclusionMortality adjustments provided by the F&R and nomogram methods are adequate and should be employed to correct mortality for loss-to-follow-up in large HIV care centres in Sub-Saharan Africa.
Highlights
The scale-up of HIV care in resource limited settings, in sub-Saharan Africa (SSA), has led to an increase in the number of centres where patients obtain combination antiretroviral therapy (ART) [2]
This study describes mortality estimates obtained from cohort of HIV infected persons receiving routine care and treatment at the Infectious Diseases Institute (IDI), hereafter referred to as the Routine Cohort
Baseline characteristics Between 1st January 2000 and 9th December 2007, a total of 19562 patients were registered for care and treatment at the IDI clinic, and of these 6398 had been initiated on ART
Summary
The scale-up of HIV care in resource limited settings, in sub-Saharan Africa (SSA), has led to an increase in the number of centres where patients obtain combination antiretroviral therapy (ART) [2]. Previous studies have shown that about 80% of patients who initiate ART are retained in care at 12 months [3]. Estimates of survival will be affected by the unavailability of data on patients who drop out of care. It is important to understand what happens to patients who drop out of care, in order to obtain less biased estimates of important HIV outcomes [5,6,7,8]. In sub-Saharan Africa, a large proportion of HIV positive patients on antiretroviral therapy (ART) are lost to follow-up, some of whom are dead. The objective of this study was to validate methods used to correct mortality estimates for loss-to-follow-up using a cohort with complete death ascertainment
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