Consistency, Reliability, and Validation of the 8-Item Morisky Medication Adherence Scale in Mexican Patients with Depressive Disorders and Type 2 Diabetes Mellitus

Background This study validates the Spanish version of the 8-Item Morisky Medication Adherence Scale (MMAS-8) among Mexican patients with depressive disorders (DD) and Type 2 Diabetes Mellitus (T2DM). Conducted with 140 participants, it highlights the scale's robust internal consistency (α = 0.88), high inter-rater reliability (κ = 0.88), and construct validity confirmed through exploratory and confirmatory factor analyses. Findings reveal a significant association between severe DD symptoms and low medication adherence (χ² = 27.32, p < 0.001). The results underscore the MMAS-8's applicability for routine clinical use and emphasize the need for integrated care addressing mental and metabolic health challenges.