Abstract
ObjectiveThe evaluation of HIV treatment programs is generally based on an estimation of survival among patients receiving antiretroviral treatment (ART). In large HIV programs, loss to follow-up (LFU) rates remain high despite active patient tracing, which is likely to bias survival estimates and survival regression analyses.MethodsWe compared uncorrected survival estimates derived from routine program data with estimates obtained by applying six correction methods that use updated outcome data by a field survey targeting LFU patients in a rural HIV program in Malawi. These methods were based on double-sampling and differed according to the weights given to survival estimates in LFU and non-LFU subpopulations. We then proposed a correction of the survival regression analysis.ResultsAmong 6,727 HIV-infected adults receiving ART, 9% were LFU after one year. The uncorrected survival estimates from routine data were 91% in women and 84% in men. According to increasing sophistication of the correction methods, the corrected survival estimates ranged from 89% to 85% in women and 82% to 77% in men. The estimates derived from uncorrected regression analyses were highly biased for initial tuberculosis mortality ratios (RR; 95% CI: 1.07; 0.76–1.50 vs. 2.06 to 2.28 with different correction weights), Kaposi sarcoma diagnosis (2.11; 1.61–2.76 vs. 2.64 to 3.9), and year of ART initiation (1.40; 1.17–1.66 vs. 1.29 to 1.34).ConclusionsIn HIV programs with high LFU rates, the use of correction methods based on non-exhaustive double-sampling data are necessary to minimise the bias in survival estimates and survival regressions.
Highlights
In the last five years, antiretroviral treatment (ART) programs have scaled-up in Sub-Saharan Africa to provide ART to millions of people
High rates of loss to follow-up represent a persistent challenge in program evaluation [6] and, there is yet no validated and commonly accepted method to analyse program data taking into account loss to follow-up data in the absence of vital registration systems
The death rate is frequently higher among LFU than among non-LFU patients for several reasons [8,9,10]: i) death can be the cause of the loss to follow-up; ii) patients prone to loss to follow-up might be frailer than the others and have higher risks of death; and, iii) after a few weeks or months without treatment, LFU patients become frailer than the others
Summary
In the last five years, antiretroviral treatment (ART) programs have scaled-up in Sub-Saharan Africa to provide ART to millions of people. High rates of loss to follow-up represent a persistent challenge in program evaluation [6] and, there is yet no validated and commonly accepted method to analyse program data taking into account loss to follow-up data in the absence of vital registration systems. Program evaluations use estimates of the probability of remaining in care considering deaths and losses to follow-up as program failures [7]. These estimates may be difficult to interpret. The death rate is frequently higher among LFU than among non-LFU patients for several reasons [8,9,10]: i) death can be the cause of the loss to follow-up; ii) patients prone to loss to follow-up might be frailer than the others and have higher risks of death; and, iii) after a few weeks or months without treatment, LFU patients become frailer than the others
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