Cultural Adaptation and Preliminary Validation of Adherence Questionnaires for Japanese Patients with Breast Cancer:...

This pilot study conducted a cultural adaptation and preliminary validation of the Beliefs about Medicines Questionnaire (BMQ) and the Medication Adherence Rating Scale (MARS) for Japanese patients with breast cancer.

The grammatical accuracy of the Japanese translations of the BMQ and MARS, which are originally in English, was assessed by 10 physicians. A pilot survey was conducted with 50 patients with breast cancer in Japan who were starting adjuvant endocrine therapy. Internal consistency was examined using item-total and item-rest correlations and Cronbach's alpha. Items with low correlations were flagged for revision or removal. Oncology experts further reviewed problematic items for clinical relevance and cultural appropriateness.

Several items showed low relevance, particularly those that were inconsistent with the Japanese healthcare context. In the BMQ, Q6 ("This medicine is a mystery to me") and Q14 ("Natural remedies are safer than medicines") had low item-rest correlations (r = 0.079 and 0.075, respectively). In the MARS, four items (Q3-Q5 and Q9) were redundant.

This pilot study demonstrated the significance of culturally adapting the BMQ and MARS. Revising or removing culturally incongruent items improved their relevance and reliability for Japanese patients with breast cancer.