The eight-item Morisky Medication Adherence Scale MMAS: translation and validation of the Malaysian version

AIMS:
To translate and examine the psychometric properties of the Malaysian version of the Morisky Medication Adherence Scale (MMAS) among patients with type 2 diabetes.

METHODS:
A standard "forward-backward" procedure was used to translate MMAS into Malay language. It was later validated on a convenience sample of 223 type 2 diabetes outpatients between May and September 2009. Reliability was tested for internal consistency. Validity was confirmed using convergent and known group validity.

RESULTS:
Employing the recommended scoring method, the mean±SD of MMAS scores was 6.13±1.72. Moderate internal consistency was found (Cronbach's α=0.675), the test-retest reliability value was 0.816 (p<0.001). A positive correlation between the eight- and four-item MMAS was found (r=0.792; p<0.01). A significant relationship between MMAS categories and HbA1c categories (χ(2)=20.261; p≥0.001) was found. The MMAS sensitivity and specificity, with positive and negative predictive values were 77.61%, 45.37%, 46.84% and 76.56%, respectively.

CONCLUSIONS:
The findings of this validation study indicate that the Malaysian version of the MMAS is a reliable and valid measure of medication adherence which can now be used.