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Standard definition of loss-to-follow-up for ART patients


A study led by Benjamin Chi of the University of Alabama, Birmingham, USA and colleagues reports on the development of a standard definition for loss-to-follow-up (LTFU) that can be used by HIV antiretroviral programs worldwide. Based on their findings, which are published in this week's PLoS Medicine, the authors recommend that the standard definition for LTFU should be when 180 days or more have elapsed since the patient's last clinic visit.

Patient attrition from antiretroviral therapy (ART) programs is recognized as a threat to the long-term success of such programs worldwide. A standardized method for classifying patients as LTFU is essential in order to be able to compare the performance of different programs, and deduce which factors are responsible for LTFU. In this study, the researchers performed a statistical analysis using data from 111 health facilities across Africa, Asia, and Latin America, categorizing patients receiving ART at each facility at a ''status classification'' date as active, or LTFU, using a range of intervals (thresholds) since their last clinic visit.

The authors found that, at a facility level, the best-performing threshold for patient classification ranged from 58 to 383 days (with an average of 150 days), but application of a 180-day threshold to individual facilities only slightly increased misclassifications. Using this 180-day interval, the average LTFU at individual facilities was 19.9%. Though the 180-day threshold produced the fewest patient misclassifications when data from all facilities were pooled, the authors acknowledge that local, national, or regional definitions of LTFU may be more appropriate in certain contexts.

Adopting this standard definition for LTFU should facilitate harmonization of monitoring and evaluation of ART programs across the world as well as helping to identify ''best practices'' that are associated with low LTFU rates. The authors note: "Further research is needed to understand individual- and facility-level predictors of LTFU, so that at-risk populations can be identified and appropriate interventions can be evaluated".

They add: "[Standardisation] provides the necessary framework for continued research to improve patient retention, so that the health gains from HIV treatment programs may be maximized and sustained".


Funding: The International Epidemiologic Databases to Evaluate AIDS (IeDEA) collaboration is funded jointly by the National Institute of Allergy and Infectious Diseases, the National Cancer Institute, and the Eunice Kennedy Shriver National Institute of Child Health and Human Development through the following grants: Central African region (U01AI069927), Eastern African region (U01AI069919), Southern African region (U01AI069924), Western African region (U01AI069919), Asia/Pacific region (U01AI069907), and Caribbean, Central American, and South American region (U01AI069923). The TREAT Asia HIV Observation Database, a contributor to the Asia/Pacific IeDEA region, is jointly supported by the Foundation for AIDS Research (amfAR), the Dutch Ministry of Foreign Affairs, and Stichting Aids Fonds. Additional salary and trainee support was provided by the US National Institutes of Health (D43-TW001035; P30-AI027767) and the Doris Duke Charitable Foundation (2007061). No funding bodies had any role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing Interests: The authors have declared that no competing interests exist.

Citation: Chi BH, Yiannoutsos CT, Westfall AO, Newman JE, Zhou J, et al. (2011) Universal Definition of Loss to Follow-Up in HIV Treatment Programs: A Statistical Analysis of 111 Facilities in Africa, Asia, and Latin America. PLoS Med 9(10): e1001111. doi:10.1371/journal.pmed.1001111


Benjamin Chi

University of Alabama at Birmingham

Centre for Infectious Disease Research in Zambia
+260 977 859 179

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