Empowering Adherence Assessment: Translating and Validating the 15-STARS Questionnaire for Use in Taiwanese Community Pharmacies.

BACKGROUND: Medication adherence is a key determinant of treatment effectiveness, yet few brief, freely available, and culturally appropriate adherence assessment tools are available in Traditional Chinese for use in routine community pharmacy practice. The 15-item Screening Tool for AdheRence to medicineS (15-STARS) is a pharmacy-based questionnaire designed to identify medication non-adherence and its underlying barriers. OBJECTIVE: To translate, culturally adapt, and validate the 15-STARS in Traditional Chinese and evaluate its utility for screening medication non-adherence and identifying barriers to adherence among patients with type 2 diabetes (T2D) in Taiwanese community pharmacies. METHODS: This cross-sectional study comprised two sequential phases: translation and cross-cultural adaptation, followed by field testing. Translation involved forward-backward translation and cognitive debriefing with pharmacists and patients. The Traditional Chinese 15-STARS was administered to adults with T2D recruited from six community pharmacies in Taiwan. Psychometric evaluation included content validity, item-level criterion validity against the Traditional Chinese Adherence to Refills and Medications Scale (ChARMS-T), and internal consistency assessed using McDonald's omega (ω). Associations among adherence, medication-related factors, and glycemic control were examined. RESULTS: Ten pharmacists and ten patients participated in cognitive debriefing, and 215 patients completed field testing. Content validity was excellent, with item-level and scale-level content validity indices of 1.00 after revision. Items 6-9 demonstrated good internal consistency (ω = 0.831), and selected 15-STARS items were significantly correlated with corresponding ChARMS-T measures. Among the participants, 53.0% of participants reported no missed medication doses during the previous two weeks, whereas 47.0% reported missing at least one dose. The most common reasons for non-adherence were forgetfulness (33.0%), concerns about taking too many medications (18.6%), and concerns about side effects (15.3%). Greater regimen complexity and higher dosing frequency were associated with lower adherence and poorer glycemic control. CONCLUSION: The Traditional Chinese 15-STARS demonstrated satisfactory content validity, evidence of criterion validity for selected items, and internal consistency among conceptually related belief-based items in Taiwanese community pharmacies. The instrument may serve as a practical screening tool for identifying patients at risk of non-adherence and exploring adherence-related barriers, thereby supporting targeted pharmacist-led interventions.