Sociodemographic, Clinical, and Psychosocial Predictors of Short- and Long-Term Study Retention in the Diabetes Prevention Program (DPP) Outcomes Study (DPPOS)
Objective: Success of longitudinal studies depends on retention of participants. We examined characteristics as predictors of retention among participants with prediabetes and type 2 diabetes (T2D) in the Diabetes Prevention Program (DPP) and the follow-up DPP Outcomes Study (DPPOS).
Research Design and Methods: 3234 adults at high risk of T2D joined the DPP (1996-1999, mean age 51±10y). They were randomized to lifestyle, metformin, or placebo intervention, and then followed through 2020. Logistic regression models estimated the association between baseline sociodemographic, clinical and psychosocial characteristics (life events, family functioning, social support) and short-term retention (~3y). Cox proportional hazards models, censoring at death, estimated the association between baseline and time-varying characteristics and time-to-dropout over the entire 20y of follow-up.
Results: Among surviving participants (N=3218), 93% were retained after 3y and 75% of surviving remained engaged over 20y. Younger age was associated with dropout during DPP and over 20y of follow-up. Female sex, non-White race/ethnicity, employment, and lack of baseline depressive symptoms were associated with better long-term retention. Over time, better health state (SF-36) (HR: 0.89 per 0.1pt; CI: 0.83-0.95) was associated with retention. Greater BMI (1.06 per 5kg/m2; CI: 1.00-1.12), more recent life events (1.08; CI: 1.02-1.14) and depressive symptoms (1.11 per 5pts; CI: 1.05-1.18) were associated with reduced retention. Among adults 45-59y at baseline, development of T2D was associated with better retention (0.75; CI: 0.58-0.97).
Conclusions: Twenty-year retention of a racially and geographically diverse cohort with prediabetes is possible. Retention was associated with age, psychosocial factors, T2D development, and BMI.
