Adherence to Inflammatory Bowel Disease Medications in Southern New Zealand

Background: Inflammatory bowel diseases (IBDs) require continuous clinical management; poor medication adherence may result in worse disease outcomes and increased healthcare costs. This study investigated medication adherence and associated risk factors in IBD patients. Methods: Otago (New Zealand) IBD patients were mailed questionnaires on demographics, medication-taking behavior, and a validated Probabilistic Medication Adherence Scale (ProMAS). Results: The response rate was 29.7% (n = 174/590). The study sample was mean (SD) 50.5 (16.9) years old, 57.9% female, 49.4% had Crohn's disease, and 43.9% ulcerative colitis, with median of 9.5 years (interquartile range: 5.0-22.0) of IBD duration. About 31.1% scored below medium adherence according to ProMAS. About 11.9%, 24.7%, and 23.1% reported failing to renew, purposely not taking, and stopping taking medications, respectively; 27.2% of those who reported having no issues taking medication scored below medium on the ProMAS. Older age was associated with higher ProMAS adherence score (Pearson's r = .25; P = .0014). There were no differences in medication adherence between the types of IBDs (P = .87), disease activity status (P =.70), or gender (P = .27). There was no correlation between the number of medications and level of adherence (Pearson's r = .09; P = .27). About 18.7%, 10.1%, and 5.0% of patients reported forgetting to take medications when traveling, when out of routine, and when busy, respectively. The most used strategies to remember medications included utilizing specific routines (40.1%) and keeping medications in specific locations (21.1%). Conclusions: A third of IBD patients had below medium medication adherence. There were discrepancies between self-reported and toolassessed medication adherence scores with over one-third of patients underestimating/overestimating their adherence. Lay Summary A third of Otago, New Zealand, IBD patients had below medium medication adherence, with adherence positively associated with age. There were discrepancies between self-reported and tool-assessed medication adherence scores with over one-third of patients underestimating or overestimating their adherence.