Predictors of Follow-Up Engagement in an Adolescent Alcohol Longitudinal Cohort

OBJECTIVE: Attrition can bias longitudinal findings, including those on alcohol use. We examined predictors of follow-up engagement in a multi-site neuroimaging cohort of youth. METHOD: Data were drawn from the first nine annual waves of the National Consortium on Alcohol and Neurodevelopment in Adolescence (NCANDA), which recruited 831 participants aged 12-21 years in 2013-2014 (52% female). Follow-up engagement was modeled as the total number of completed follow-up visits (0-9, excluding baseline) using Poisson regression with multiple imputation and family-cluster-robust standard errors. Secondary analyses examined categorical engagement levels. Primary predictors included exceeding age- and sex-specific baseline alcohol use thresholds, externalizing symptoms, race, and demographic and family factors. RESULTS: Overall engagement was high, with participants completing an average of approximately 9 of 10 possible visits. In Poisson models, exceeding baseline alcohol use thresholds was associated with a modest reduction in follow-up visits, although this did not reach statistical significance (IRR = 0.940, 95% CI: 0.881-1.004, p = .064). Externalizing symptoms were not significantly associated with engagement (IRR = 1.001, 95% CI: 0.998-1.003, p = .647). Sibling co-enrollment was associated with greater engagement (IRR = 1.058, 95% CI: 1.021-1.097, p = .002), while other factors showed small or non-significant associations. CONCLUSIONS: Follow-up engagement was generally high across adolescence into young adulthood. Exceeding baseline alcohol use thresholds showed a modest association with reduced engagement, although not statistically significant in the count model. Externalizing symptoms were not associated with engagement. Categorical analyses suggested a stronger association between exceeding baseline alcohol use thresholds and lower engagement groups. These findings may help identify participants who could benefit from additional engagement efforts.