Reliability and validity of a modified 8-item Morisky Medication Adherence Scale in patients with chronic pain

Background: The 8-item Morisky Medication Adherence Scale (MMAS-8) is a simple, economic and easy tool to evaluate the medication compliance of chronic disease. The reliability and validity of the MMAS-8 in patients with chronic pain were unclear. Therefore, we aimed to validate the MMAS-8 for detecting nonadherent patients with chronic pain. Methods: A modified MMAS-8 was used to assess the medication compliance of patients with chronic pain who were treated at our hospital from July 2018 to October 2018. Cronbach's alpha was used to evaluate the internal consistency, and a factor analysis was used to examine the construct validity. Convergent validity was assessed by comparing the MMAS-8 and a medication adherence visual analog score (MA-VAS) through Pearson's correlation coefficient. Results: A total of 113 patients were evaluated. The (t-test) results revealed that there was a significant difference in average scores between the low-score group (who scored less than 5 points) and the high-score group (who scored 8 points or above), indicating that the scale displayed a good degree of discrimination. Except for Items 4 and 5, all the other items exhibited a good correlation with the total score (correlation coefficient >0.5; P<0.05). The Cronbach's alpha coefficient was 0.625, indicating that the scale's internal consistency was relatively satisfactory. Two common factors, which explained 62.978% of the total variance, were extracted by factor analysis to examine the construct validity of the MMAS-8, and the load of the 6 items was greater than 0.4. The Pearson correlation coefficient was 0.845 (P<0.001); thus, convergent validity was high. Conclusions: The modified MMAS-8 exhibited acceptable reliability and validity in evaluating medication compliance in patients with chronic pain; thus, it can be applied to detect nonadherent patients with chronic pain.

Automated summary

The study validated the modified MMAS-8 for assessing medication compliance in patients with chronic pain, demonstrating acceptable reliability and validity for detecting nonadherent patients.