Phone-delivered PSST was feasible and acceptable. Efficacy estimates were similar to those of lengthier interventions conducted in other chronic illness populations. Older adolescents benefited more from the intervention than their younger counterparts.

Distinct classes of adherence trajectories in pediatric IBD can be identified with longitudinal data collection approaches; however, disease and regimen factors offered limited value in predicting adherence trajectory class. Future research should utilize longitudinal conceptualizations of adherence and examine alternative predictors of declining adherence over time.

Findings highlight the importance of evaluating and addressing nonadherence to vitamin and mineral supplements in youth with pediatric IBD.