Psychometric Properties of Persian Version of the 8-item Morisky Medication Adherence Scale in Type 2 Diabetes Patients

Abstract

Introduction: The 8-items Morisky Medication Adherence Scale (MMAS-8) is a brief questionnaire that is applied to assess medication-taking behaviours. Aim: To evaluate the validity and reliability of the Persian version of MMAS-8 among Type 2 Diabetes Mellitus (T2DM) patients in Iran. Materials and Methods: A cross-sectional study was conducted among 589 T2DM patients in Kerman city (southeast Iran) from January to March 2017. Data were collected using MMAS-8 and diabetes self-management questionnaires. To check test re-test reliability and to determine the internal consistency Intra-class Correlation Coefficient (ICC) and Cronbach’s alpha method were employed. Also, convergent validity was assessed by correlation analysis method. Results: Cronbach’s alpha and ICC of MMAS-8 were 0.75 and 0.88, respectively. The correlation coefficient between MMAS-8 and medication adherence subscale of diabetes selfmanagement questionnaire was 0.85 (p<0.001). Exploratory Factor Analysis (EFA) showed two factors for MMAS-8. The first factor included items 1, 2, 3, 4, 6, and 8. Moreover, items 5 and 7 fell in the second factor. Confirmatory Factor Analysis (CFA) indices for modified MMAS-8 without Items 5 and 7 model (X2=9.3, DF=6, P=0.15, CFI=0.99, RMSEA=0.04, TLI=0.98, and NFI=0.98) were acceptable. Conclusion: In this study, the Persian version of MMAS-8 was investigated to find out whether it is a reliable and valid scale for assessing medication-taking behaviours in T2DM patients. The results showed that it can be applied for Iranian diabetic patients by health care providers and researchers.

Keywords

• compliance
• morisky scale
• validation