Who Is Enrolling? The Path to Monitoring in Type 1 Diabetes TrialNet's Pathway to Prevention.

Objective: To better understand potential facilitators of individual engagement in type 1 diabetes natural history and prevention studies through analysis of enrollment data in the TrialNet Pathway to Prevention (PTP) study.

Research Design And Methods: We used multivariable logistic regression models to examine continued engagement of eligible participants at two time points: ) the return visit after screening to confirm an initial autoantibody-positive (Ab) test result and ) the initial oral glucose tolerance test (OGTT) for enrollment into the monitoring protocol.

Results: Of 5,387 subjects who screened positive for a single autoantibody (Ab), 4,204 (78%) returned for confirmatory Ab testing. Younger age was associated with increased odds of returning for Ab confirmation (age <12 years vs. >18 years: odds ratio [OR] 2.12, < 0.0001). Racial and ethnic minorities were less likely to return for confirmation, particularly nonwhite non-Hispanic (OR 0.50, < 0.0001) and Hispanic (OR 0.69, = 0.0001) relative to non-Hispanic white subjects. Of 8,234 subjects, 5,442 (66%) were identified as eligible to be enrolled in PTP OGTT monitoring. Here, younger age and identification as multiple Ab were associated with increased odds of returning for OGTT monitoring (age <12 years vs. >18 years: OR 1.43, < 0.0001; multiple Ab: OR 1.36, < 0.0001). Parents were less likely to enroll into monitoring than other relatives (OR 0.78, = 0.004). Site-specific factors, including site volume and U.S. site versus international site, were also associated with differences in rates of return for Ab confirmation and enrollment into monitoring.

Conclusions: These data confirm clear differences between successfully enrolled populations and those lost to follow-up, which can serve to identify strategies to increase ongoing participation.