Risk Factors for Medication Non-Adherence to Biologic Therapy in Patients With Inflammatory Bowel Disease: A Retrospective Analysis

Abstract

Introduction: In inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), adherence to biologic therapy is critical. Prior research has demonstrated that a medication possession ratio (MPR) of less than 0.86 significantly increases the risk of disease flare. (1) Further understanding of the risk factors for non-adherence is needed. Methods: We conducted a retrospective study to evaluate patients (pts) treated at a tertiary care IBD center prescribed injectable biologic therapy (adalimumab, certolizumab, golimumab, or ustekinumab) and followed by the center's specialty pharmacy (defined as at least 3 prescription claims). MPR was calculated as the sum of days' supply for all prescription claims divided by the total number of days (d) elapsed during the study period. Medication non-adherence was defined as MPR < 0.86. Wilcoxon test was used for continuous variables, Pearson testing for categorical variables in univariate analysis. Results: In this study, 460 pts (n=393 with CD and n=67 with UC) were evaluated. Table 1 summarizes patient characteristics. Median follow up was 921 d (range 232, 1414 d). The overall mean MPR was 0.89. In this cohort, 69% of pts were adherent (MPR > 0.86), 71% of pts with CD and 87% of pts with UC. Several risk factors were shown to increase the risk of non-adherence in univariate analysis including a diagnosis of CD, insurance type, psychiatric history, smoking, prior biologic use, and narcotic use (Table 2). Disease type and past surgical history in CD did not have an impact on adherence. Using multivariate analysis, insurance type (Medicaid) (OR 5.5, CI 1.85, 15.6) and diagnosis of CD (OR 2.8, CI 1.3, 6.0) increased the risk of noncompliance, but several risk factors trended toward significance. In pts with CD, as the number of risk factors present increased (narcotic use, psychiatric diagnosis history, prior biologic use, and smoking), the probability of non-adherence significantly increased. (Figure 2) Adherence was 77% and 73% in patients with 0 to 1 risk factors, decreasing to 65%, 61% and 37% in those with 2, 3, or 4 risk factors respectively (p < 0.05).570_B Figure 2. Risk Factors for non-adherence in pts with IBD on injectable biologic medicationConclusion: This study identified several risk factors for non-adherence to injectable biologic therapy. Additionally, as number of risk factors increased in pts with CD, the probability of adherence to therapy significantly decreased.570_A Figure 1. Patient Characteristics570_C Figure 3. The probability of adherence in pts with CD decreases as the number of risk factors increase (risk factors include prior biologic use, narcotic use, psychiatric history, and smoking; p < 0.05).