Validation and psychometric properties of the 8-item Morisky Medication Adherence Scale (MMAS-8) in Type 2 diabetes patients in sub-Saharan Africa

Abstract

Objectives: Research in the field of adherence to medications has not been explored in sub-Saharan Africa. The goal of this manuscript is to (1) validate the use of an adherence tool: a translated 8-item Morisky Medication Adherence Scale (MMAS-8) for Type 2 diabetes and (2) assess association between levels of adherence and psychometric properties.

Methods: 154 Type 2 diabetic patients being chronically treated were surveyed from Togolese Diabetes Association using a demographic survey, 4-item Morisky Medication Adherence Scale (MMAS-4) and MMAS-8 from January to March 2012.

Results: Internal reliability for the 8-item scale showed the Cronbach alpha being 0.47. The MMAS-8 and MMAS-4 showed a Pearson's correlation of 0.6851. For known groups validity, the chi-square (χ(2)) tests of proportions showed a significant relationship between blood glucose control and MMAS-8 (χ(2)=12.17; p=0.002). The sensitivity, specificity, positive predictive value and negative predictive value were 75%, 48.39%, 56.76%, and 68.18% respectively.

Conclusions: Psychometric analyses showed that the MMAS-8 was a suitable way of measuring medication adherence in the study population given its low cost, ease of use, and the low income status of the country.

Keywords: Adherence; Diabetic medications; Morisky Scale; Sub-Saharan Africa; Togo.