Self-reported medication adherence and disease activity in pediatric eosinophilic esophagitis: lessons from a real-world cohort.

Medication adherence is a modifiable determinant of successful therapy. Adhering to pharmacologic regimens to treat eosinophilic esophagitis (EoE) can be complicated and burdensome, yet the impact of medication adherence, particularly the self-reported adherence, on EoE activity indices remains understudied. We assessed the association between self-reported adherence to pharmacologic EoE therapy and endoscopic (EoE Endoscopic Reference Score, EREFS; range = 0-9), histologic (peak eosinophil count), and multidimensional Index of Severity for EoE in a prospectively followed pediatric cohort between 2017 and 2024, cross-sectionally and longitudinally, with up to three EGD time points. Self-reported adherence was collected during routine pre-EGD assessment as a percentage of the inter-EGD interval (12-16 weeks). Hierarchical variable clustering was applied to reduce multicollinearity. Our cohort comprised 103 children with an index EGD (EGD 1); 36 and 19 had EGDs at time points 2 and 3, respectively. At EGD 1, children with abnormal esophageal mucosa (EREFS ≥1) had 8% lower self-reported adherence (95% CI: 1-15%; P = 0.02) than those with normal esophageal mucosa (EREFS = 0). Additionally, for each 5-year increase in age, the self-reported adherence decreased by 5% (95% CI: 1-10%; P = 0.05). These trends persisted over time between EGD 1 and EGD 2. Self-reported adherence was not associated with peak eosinophil count, Index of Severity for EoE score, or complexity of pharmacologic regimen. Despite a median adherence of >95%, more than half had active EoE, highlighting the limited reliability of self-report alone. These findings suggest that self-reported adherence aligns with endoscopic, but not with histologic, disease activity and decreases with age, underscoring the need for age-appropriate adherence counseling and objective adherence monitoring in pediatric EoE management.