The development of a standard definition for loss-to-follow-up (LTFU) that can be used by HIV antiretroviral programs worldwide is being reported in a study by Benjamin Chi of the University of Alabama, Birmingham, USA and colleagues.
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".