Factors Associated with Attrition of Adult Participants in a Longitudinal Database: A National Institute on Disability, Independent Living, and Rehabilitation Research Burn Model System Study.

Participant attrition in longitudinal studies can lead to substantial bias in study results, especially when attrition is nonrandom. A previous study of the Burn Model System (BMS) database prior to 2002 identified participant and study-related factors related to attrition. The purpose of the current study was to examine changes in attrition rates in the BMS longitudinal database since 2002 and to revisit factors associated with attrition. Individuals 18 years and older enrolled in the BMS database between 2002 and 2018 were included in this study. Stepwise logistic regression models identified factors significantly associated with attrition at 6, 12, and 24 months postburn injury. The percentage of individuals lost to follow-up was 26% at 6 months, 33% at 12 months, and 42% at 24 months. Factors associated with increased risk of loss to follow-up across two or more time points include male sex, lower TBSA burn size, being unemployed at the time of burn, shorter duration of acute hospital stay, younger age, not having private health insurance or workers' compensation, and a history of drug abuse. Retention levels in the BMS have improved by at least 10% at all time points since 2002. The BMS and other longitudinal burn research projects can use these results to identify individuals at high risk for attrition who may require additional retention efforts. Results also indicate potential sources of bias in research projects utilizing the BMS database.