Utility of the MARS-5 in Assessing Medication Adherence in IBD

Introduction: We aimed to validate the Medication Adherence Report Scale-5 (MARS-5) as a tool for assessing medication adherence in inflammatory bowel disease (IBD) and to determine predictors of medication adherence.

Methods: One hundred twelve (N = 112) adults with confirmed IBD participating in the longitudinal Manitoba Living With IBD Study were eligible. Demographics, IBD type, surgeries, disease activity (using the Inflammatory Bowel Disease Symptom Inventory and fecal calprotectin levels), perceived stress, and medication use were collected biweekly through online surveys. The MARS-5 scores were obtained at baseline and at 1 year. Correlation between medication monitoring data and MARS-5 scores was performed and the optimal MARS-5 cutoff point for adherence assessment determined. Predictors of medication adherence were assessed at both ≥90% and ≥80%.

Results: Participants were predominantly female (71.4%), mean age was 42.9 (SD = 12.8), and the majority (67.9%) had Crohn disease (CD). Almost half (46.4%) were taking more than 1 IBD medication, with thiopurines (41.9%) and biologics (36.6%) the most common. Only 17.9% (n = 20) were nonadherent at a <90% level; of those, 90% (n = 18) were using oral medications. The MARS-5 was significantly associated with adherence based on medication monitoring data at baseline (r = 0.48) and week 52 (r = 0.57). Sensitivity and specificity for adherence ≥80% and ≥90% were maximized at MARS-5 scores of >22 and >23, respectively. Having CD (OR = 4.62; 95% confidence interval, 1.36-15.7) was the only significant predictor of adherence.

Conclusion: MARS-5 is a useful measure to evaluate adherence in an IBD population. In this highly adherent sample, disease type (CD) was the only predictor of medication adherence.