Objectives: Nonadherence is an issue in the management of inflammatory bowel disease (IBD), and no validated screening tool is available. We aimed to determine whether scores from a self-reported adherence survey correlated with pharmacy refill data as a reliable measure of medication adherence.
Methods: We used the eight item, self-reported Morisky Medication Adherence Scale. Each question is worth a point, with a maximum score of 8. Pharmacies were contacted for refill information for the previous 3 months, then 3 and 6 months from enrollment. Refill data were recorded for each time interval as the medication possession ratio (MPR); adherence was defined as >80%. Analysis of variance was used to determine the relationship between survey scores and MPR by drug class.
Results: One hundred fifty outpatients were enrolled, of whom 94 had Crohn's disease and 56 had ulcerative colitis; 89 were female. At baseline, 47% of patients were on 5-aminosalicylic acid (5-ASA), 54% an immunomodulator, 15% infliximab, 8% an injectable biologic, and 6% budesonide. The median adherence score was 7. Fifty-two percent stated they "rarely" missed a dose of medication. The median adherence score, as defined by refill data, ranged from 0% (injectable biologic) to 75% (infliximab) by drug class. Only those on an immunomodulator had a survey score that positively correlated with adherence.
Conclusions: Only those on a thiopurine were likely to have a score predicting adherence behavior. Adherence to therapy for IBD is complex and cannot be predicted reliably by a self-reported survey tool validated for other chronic conditions.