Medication refills do not guarantee medication intake: translation and validation of the Adherence to Refills and Medications Scale in Traditional Chinese among individuals with type 2 diabetes in Taiwan

Objective: This study aimed to translate and validate the Adherence to Refills and Medications Scale into Traditional Chinese (ChARMS-T) and to investigate common barriers to medication adherence among patients with type 2 diabetes (T2D) in Taiwan. Methods: The ChARMS-T was developed through translation and application phases. During the translation phase, the scale underwent forward translation, backward translation, and cognitive debriefing. In the application phase, the finalized ChARMS-T was administered to patients with T2D at five Taiwan community pharmacies over eleven months starting in June 2023. Psychometric properties were assessed using criterion validity, construct validity through confirmatory factor analysis, and reliability through McDonald’s omega. Results: A total of 343 participants completed surveys. Factor analysis of the 12-item ChARMS-T revealed two dimensions: medication-taking (8 items) and medication refill (4 items). The instrument demonstrated acceptable internal consistency, with McDonald’s omega scores of 0.841 for medication-taking and 0.647 for medication refill. The medication refill subscale showed strong agreement with the objective refill measure, proportion of days covered, with a coefficient of 0.84, suggesting that these measures evaluate similar constructs. Evidence of known-groups validity was demonstrated by a significant difference between ChARMS-T scores and glycemic control (p = 0.047). Patients with good glycemic control had a significantly higher adherence rate to both refills and medication-taking compared to those with poor glycemic control. The most frequently reported barriers to medication-taking were carelessness (55.7%), forgetfulness (54.8%), and frequent dosing intervals (43.1%). For medication refills, 9.6% of the participants identified a lack of planning as the main reason for not refilling their diabetes medications on time, followed by forgetfulness (7.6%). Conclusions: The ChARMS-T identified a broader range of non-adherence reasons and demonstrated good psychometric properties. It can be integrated into practice settings for screening and follow-up to enhance medication adherence through effective communication between healthcare professionals and patients, ultimately improving long-term patient health outcomes.