Five-year attrition, active enrollment, and predictors of level of participation in the Longitudinal Assessment of Bariatric Surgery (LABS-2) study

Reporting high-quality bariatric surgery outcomes depends on participant attrition and level of study participation among enrolled participants.Our aims are to report participant attrition, active enrollment, and level of participation, and to evaluate pre-surgery sociodemographic, physical health, and psychosocial factors as predictors of attrition and level of participation through 5 years.The Longitudinal Assessment of Bariatric Surgery-2 study which enrolled 2458 adults undergoing a first bariatric surgical procedure at 1 of 6 US cites from 2006 through 2009.In-person research assessments were conducted pre-surgery and annually for five years. Extensive retention strategies including offering remote assessments (telephone, email, mail, or a combination) were fully implemented in 2009. Among living participants, including those inactivated, annual follow-up assessments were categorized as in-person, remote or missed through 5 years.By year 5, 1.7% of participants had died and 3.2% had withdrawn or were inactivated by the study staff; thus, attrition was 4.9% (n = 121). Controlling for site and calendar year, missed assessments increased from 14.7%-21.8% between years 1 and 2 and then stayed relatively stable (20.8%-19.6%) for years 3-5. Younger age, male sex, White race, lower body mass index, smoking, illicit drug use, and higher weight loss expectations preoperatively were independently associated with a higher likelihood of a missed versus in-person assessment across follow-up.The LABS-2 participant attrition was low. The percentage of missed assessments did not increase after year 2, perhaps due to implementation of a comprehensive retention plan. Predictors of missed assessments highlight subgroups to target for focused retention efforts.