Reliability and validity of the Chinese version of the eight-item Morisky Medication Adherence Scale in Chinese patients with systemic lupus erythematosus

Abstract

Objective: To evaluate the reliability and validity of the Chinese version of the eight-item Morisky Medication Adherence Scale (MMAS-8) in Chinese patients with systemic lupus erythematosus (SLE).

Methods: The survey was conducted with a consecutive sampling of 158 Chinese SLE patients attending public hospitals from January to March 2021. We used the translated Chinese version of the MMAS-8 to collect related data. Reliability, item, and factor analyses were used to test the reliability and validity of the MMAS-8 scale in the selected patients. The internal consistency reliability was evaluated using Cronbach's α coefficient. Test-retest reliability was assessed using intraclass correlation coefficients (ICCs) in a subset of 30 participants. Construct validity was evaluated using confirmatory factor analysis and correlations between the Self-efficacy for Appropriate Medication Use Scale (SEAMS) and related measures.

Results: The internal consistency reliability of the Chinese version of the MMAS-8 was high (Cronbach's α = 0.817), and the test-retest reliability was excellent (intraclass correlation = 0.947; P < 0.001). There were significant differences in the F test and t test between the two extreme groups before and after the ranking of 27% of the questionnaire scores (P < 0.001). The Kaiser-Meyer-Olkin (KMO) value of construct validity was 0.860. The spherical test value of Bartlettgers was 417.8822. Factor analysis yielded three components that accounted for 69.375% of the total variance. Exploratory factor analysis identified three dimensions of the Chinese version of the MMAS-8. In terms of criterion validity, the correlation of the MMAS-8 score in SEAMS indicated that the convergent validity was good (r = 0.926; P < 0.001).

Conclusions: This study shows that the Chinese version of the Medication Adherence Scale-8 is a reliable and valid tool for assessing medication adherence in Chinese SLE patients. Key Points • Many factors affect medication adherence in SLE patients. • Many questionnaires measure medication adherence levels. • There is a lack of reliable validation of medication adherence questionnaires specifically for SLE patients.

Keywords: Adherence scale; Drug compliance; Morisky medication; Reliability; SLE patients; Validity.