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. 2013 Sep;66(9):1006-13.
doi: 10.1016/j.jclinepi.2013.03.013. Epub 2013 Jun 15.

Impact of definitions of loss to follow-up (LTFU) in antiretroviral therapy program evaluation: variation in the definition can have an appreciable impact on estimated proportions of LTFU

Anna Thora Grimsrud  1 , Morna Cornell, Matthias Egger, Andrew Boulle, Landon Myer
Affiliations

Impact of definitions of loss to follow-up (LTFU) in antiretroviral therapy program evaluation: variation in the definition can have an appreciable impact on estimated proportions of LTFU

Anna Thora Grimsrud et al. J Clin Epidemiol. 2013 Sep.

Abstract

Objective: To examine the impact of different definitions of loss to follow-up (LTFU) on estimates of program outcomes in cohort studies of patients on antiretroviral therapy (ART).

Study design and setting: We examined the impact of different definitions of LTFU using data from the International Epidemiological Databases to Evaluate AIDS-Southern Africa. The reference approach, Definition A, was compared with five alternative scenarios that differed in eligibility for analysis and the date assigned to the LTFU outcome. Kaplan-Meier estimates of LTFU were calculated up to 2 years after starting ART.

Results: Estimated cumulative LTFU were 14% and 22% at 12 and 24 months, respectively, using the reference approach. Differences in the proportion LTFU were reported in the alternative scenarios with 12-month estimates of LTFU varying by up to 39% compared with Definition A. Differences were largest when the date assigned to the LTFU outcome was 6 months after the date of last contact and when the site-specific definition of LTFU was used.

Conclusion: Variation in the definitions of LTFU within cohort analyses can have an appreciable impact on estimated proportions of LTFU over 2 years of follow-up. Use of a standardized definition of LTFU is needed to accurately measure program effectiveness and comparability between programs.

Keywords: Antiretroviral therapy; Cohort; Loss to follow-up; Program outcomes; Retention; Survival analysis.

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Conflict of interest statement

Conflict of Interest/Financial Disclosure: None.

Figures

Fig. 1
Fig. 1
Decision in defining LTFU in an antiretroviral therapy program cohort analysis. *Bolded option denotes decision illustrated in Definition A. LTFU, loss to follow-up.
Fig. 2
Fig. 2
Antiretroviral therapy program LTFU by LTFU definition 0–24-months follow-up. LTFU, loss to follow-up.
See this image and copyright information in PMC

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