The Need for Double-Sampling Designs in Survival Studies:An Application to Monitor PEPFAR

Abstract

In 2007, there were 33.2 million people around the world living with HIV/AIDS (UNAIDS/WHO, 2007). InMay 2003, the U.S. President announced a global program, known as the President’s Emergency Plan for AIDS Relief(PEPFAR), to address this epidemic. We seek to estimate patient mortality in PEPFAR in an effort to monitor and evaluatethis program. This effort, however, is hampered by loss to follow-up that occurs at very high rates. As a consequence, standardsurvival data and analysis on observed nondropout data are generally biased, and provide no objective evidence to correctthe potential bias. In this article, we apply double-sampling designs and methodology to PEPFAR data, and we obtainsubstantially different and more plausible estimates compared with standard methods (1-year mortality estimate of 9.6%compared to 1.7%). The results indicate that a double-sampling design is critical in providing objective evidence of possiblenonignorable dropout and, thus, in obtaining accurate data in PEPFAR. Moreover, we show the need for appropriate analysismethods coupled with double-sampling designs.