Comparison of individual perceptions of medication costs and benefits between intentional and unintentional medication non-adherence among Japanese patients

Objective: To identify Japanese patients' perceptions of the costs and benefits of their medications by administering a questionnaire validated in Western patients and to compare the association between the perception levels and non-adherence to medication in the two non-adherent patient types, intentional, and unintentional. Methods: Japanese patients with chronic diseases were given a questionnaire and interviewed, and the validity and reliability of the scales generated were assessed. Logistic regression was used to analyse the association between individual perception levels and non-adherence to the medication regimen. Results: From 151 responses, two kinds of scales were generated following a report of Western patients; the necessity scale showed satisfactory reliability (Cronbach's alpha 0.79) but the concerns scale did not. Individual levels of perception of the necessity of medications were associated with unintentional non-adherence (the higher the level, the lower the odds ratio 1.0, 0.56, 0.40, and 0.15), while they were not associated with intentional non-adherence. Conclusion: Japanese patients' perceptions of the benefits of medications, but not the costs were similar to those of Western patients, and these perceptions were likely to be different between intentionally and unintentionally non-adherent patients. Practice Implications: Strategies to improve non-adherence should be designed according to the non-adherent type.