A screening instrument to identify ulcerative colitis patients with the high possibility of current non-adherence to aminosalicylate medication based on the Health Belief Model: a cross-sectional study

BACKGROUND: Non-adherence to aminosalicylates is observed among 30% to 45% of patients with ulcerative colitis and increases the risk of relapse. The Health Belief Model is a theoretical model that could offer a broader perspective to improve patients’ self-medication adherence. This study aimed to develop a screening instrument based on the Health Belief Model to screen patients with ulcerative colitis who had a high possibility of current non-adherence to aminosalicylates. The study was also designed to allow examination of factors of non-adherence. METHODS: A multicenter, cross-sectional study was conducted in outpatients diagnosed with ulcerative colitis and prescribed aminosalicylates. Non-adherence was defined as taking less than 80% of the prescribed dose. We hypothesized that there was a significant relationship between current aminosalicylate non-adherence and five components of the HBM: beliefs about taking aminosalicylates, disease characteristics, medication characteristics, abdominal symptoms, and sociodemographic characteristics. A logistic regression model was applied and the coefficients converted to a numeric scores in order to develop a screening instrument which could reliably discriminate non-adherent and adherent subjects. RESULTS: Non-adherence was observed in 127 (29.6%) of the 429 enrolled subjects. Lower perceptions of belief in taking aminosalicylates, absence of visible bleeding, eight daily tablets or less taken, and no concomitant use of thiopurines were related to non-adherence. We then developed a screening instrument comprising 22 items. When the cut-off point was set at 60, the instrument showed 85.0% sensitivity and 69.2% specificity with an area under the curve of 0.84 (95% confidence interval = 0.79–0.91). CONCLUSIONS: The instrument appeared to be reliable for identifying patients with a high possibility of current non-adherence to aminosalicylates. Further, the instrument may provide useful information for detecting patients with a high possibility of current non-adherence and for assessing factors of non-adherence. On the other hand, we need to evaluate disease activity more strictly and examine whether it is included in the screening instrument in the future. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12876-014-0220-z) contains supplementary material, which is available to authorized users.