Abstract
BACKGROUND: We evaluated the association of demographic and clinical characteristics with participation in an epidemiologic study of diabetes mellitus among youth. METHODS: SEARCH for Diabetes in Youth is a multicenter study of physician-diagnosed diabetes in youth under the age of 20 comprising a surveillance and a cohort component. At each center, we enumerated all prevalent cases of diabetes in 2001 (n=6266) and all incident cases between 2002 and 2004 (n=3668). After confirmation of eligibility and validation, we invited each case to complete a survey and participate in a study visit. Here we evaluate how age, sex, race, and diabetes type are associated with participation in the survey and study visit. RESULTS: Among prevalent cases, participation in the survey was 68% and 41% in the study visit. Among 2002 to 2004 incident cases, participation varied for the survey (76%, 81%, and 82%) and study visit (52%, 60%, and 60%). In multivariate logistic regression analyses among all incident cases, older age was associated with a lower odds of participation in the study visit (15-17 vs. <10 years: OR 0.5, 95% CI 0.4-0.7; 18-19 vs. <10 years: OR 0.3, 95% CI 0.2-0.5), as was having type 2 diabetes vs. type 1 diabetes (OR 0.5, 95% CI 0.4-0.7) and being of African American race vs. non-Hispanic White (OR 0.6, 95% CI 0.4-0.8). Results were very similar among prevalent cases. CONCLUSIONS: Elucidating the relationship between individual characteristics and participation is essential for evaluating nonresponse bias, correcting for it, and for planning and implementing recruitment strategies.