Multicenter Study of Nonadherence to Self-Injectable Biologic Therapy in Patients With Inflammatory Bowel Disease: Risk Factors and Outcomes

Background and Aims: This study aimed to evaluate adherence to subcutaneous biologic therapy and impact of nonadherence including risk factors and outcomes in academic centers with integrated specialty pharmacies for patients with inflammatory bowel disease (IBD). Methods: This was a multicenter, retrospective cohort analysis of patients aged ≥18 years receiving care in 3 tertiary care outpatient IBD clinics with integrated specialty pharmacies. Subjects were prescribed injectable anti-TNF therapy (adalimumab, certolizumab, golimumab) or anti-IL 12/23 therapy (ustekinumab) with at least 3 consecutive prescription claims. The primary outcomes were medication possession ratio (MPR), percent achieving optimal adherence (MPR > 0.86); in addition, we sought to verify a prior risk factor model including smoking status, narcotic use, psychiatric history, and prior biologic use. Secondary outcomes included emergency department visits (ED) and IBD-related hospitalizations. Statistical analysis was performed using Wilcox rank sum test, Pearson's Chi-squared test, and logistic regression model as an unordered, factor variable to flexibly estimate the probabilities of adherence. Results: Six hundred eight subjects were included. Overall median MPR was 0.95 (interquartile range 0.47, 1) and adherence was 68%–70%. When the number of risk factors for nonadherence increased, the likelihood of nonadherence increased (P <.05). In unadjusted and adjusted analysis, nonadherence increased the likelihood of ED visits [rate ratio 1.45 (95% confidence interval 1.05, 1.97)] and hospitalizations [rate ratio 1.60 (95% confidence interval 1.16, 2.10)]. Conclusion: Academic centers with integrated pharmacies had high adherence. Prior risk factors for nonadherence remained significant in this multicenter model. Nonadherence was associated with higher likelihood of hospitalizations and ED visits.