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% ( = 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 = .25; = .0014). There were no differences in medication adherence between the types of IBDs ( = .87), disease activity status ( = .70), or gender ( = .27). There was no correlation between the number of medications and level of adherence (Pearson's = .09; = .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 tool-assessed medication adherence scores with over one-third of patients underestimating/overestimating their adherence.