Comparison of methods to correct survival estimates and survival regression analysis on a large HIV African cohort

PLoS One. 2012;7(2):e31706. doi: 10.1371/journal.pone.0031706. Epub 2012 Feb 23.


Objective: The 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.

Methods: We 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.

Results: Among 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).

Conclusions: In 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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Africa
  • Algorithms
  • Anti-Retroviral Agents / therapeutic use*
  • Cohort Studies
  • Female
  • HIV Infections / epidemiology
  • HIV Infections / mortality*
  • HIV Infections / therapy*
  • Humans
  • Malawi
  • Male
  • Middle Aged
  • Models, Statistical
  • Regression Analysis
  • Survival Analysis
  • Time Factors
  • Treatment Outcome


  • Anti-Retroviral Agents