Italian version of the General Medication Adherence Scale (GMAS): translation, adaptation, and validation

Medication adherence, defined as the extent to which a patient's behaviour aligns with medical recommendations, is crucial in managing chronic diseases. Despite its importance, global adherence rates are suboptimal, with non-adherence leading to poor clinical outcomes and increased healthcare costs. The General Medication Adherence Scale (GMAS) is a self-report tool widely used to assess adherence across cultural contexts. However, no validated Italian version exists. This study aimed to translate and validate the GMAS in Italian, ensuring its reliability and cultural relevance for Italian patients with chronic conditions.

A multicenter observational study was conducted across three Italian hospitals. The translation adhered to international guidelines, encompassing initial translation, synthesis, back-translation, and expert review. A test was conducted with 30 patients. The psychometric properties of the Italian GMAS were assessed using Cronbach's alpha, intraclass correlation coefficients (ICC), and construct validity.

A total of 389 patients participated, demonstrating acceptable internal consistency (Cronbach's alpha = 0.758) and good test-retest reliability (ICC=0.859). The GMAS effectively differentiated adherence levels across various demographic and clinical factors, thereby confirming its construct validity.

The Italian GMAS is a feasible and preliminarily valid tool for assessing medication adherence. It provides a standardized approach for clinical and research settings in Italy. Its use can enhance chronic disease management by enabling healthcare professionals to identify and address adherence barriers effectively.