Adherence to Inflammatory Bowel Disease Medications in Southern New Zealand

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.

Otago (New Zealand) IBD patients were mailed questionnaires on demographics, medication-taking behavior, and a validated Probabilistic Medication Adherence Scale (ProMAS).

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%).

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.