Psychometric Properties of the Simplified Chinese Version of the Malaysian Medication Adherence Scale (C-MALMAS) on Elderly Patients

Abstract

Summary: Background: Poor medication adherence is a concern among elderly patients. One of the convenient measures of medication adherence is by using a validated instrument. Therefore, this study aimed to examine the psychometric properties of the Simplified Chinese version of the Malaysian Medication Adherence Scale (C-MALMAS) for assessing medication adherence of elderly patients. Methods: The C-MALMAS consists of 8 items which measure one domain. It was translated into the Simplified Chinese version and validated on a convenience sample of 100 elderly outpatients in Malaysia. Internal consistency of the C-MALMAS was evaluated based on Cronbach's alpha value. A retest was conducted a month later to assess its stable reliability. Validity was assessed using convergent validity by comparing C-MALMAS to the Simplified Chinese translation of the 8-item Morisky Medication Adherence Scale (MMAS-8) and concurrent validity was confirmed by comparing the medication adherence determined using C-MALMAS with that using pill count. Results: The C-MALMAS has an acceptable internal consistency, with Cronbach's alpha of 0.586 and a test-retest correlation of 0.405 (p < 0.001), indicating fair correlation. A good correlation between the C-MALMAS and MMAS-8 was found (Spearman's rho = 0.717; p < 0.001). A significant association between medication adherence based on the C-MALMAS and pill count was observed. The C-MALMAS has a sensitivity and specificity of 94.4% and 33.3%, respectively, with positive and negative predictive values of 67.3% and 80.0%, respectively. Conclusion: C-MALMAS is a reliable and valid instrument for measuring medication adherence of elderly patients, especially when a specific recall period is required. Keywords: elderly, MALMAS, medication adherence, validation