Validity and Reliability Study of the Turkish Version of the Medication Adherence Rating Scale

Background: In individuals with chronic health conditions, adherence to medication therapy is the most fundamental component of self-management. Therefore, it is essential to assess patients' medication adherence using valid and reliable tools.

Aim: The purpose of this study is to test the validity and reliability of the Turkish version of the Medication Adherence Rating Scale (MARS).

Methods: Data for this descriptive and methodological study were obtained from patients with at least one chronic condition between April and June 2024. The Turkish version of the MARS was developed utilizing the translation-back translation methodology. The content validity ratio was determined through expert evaluations. The construct validity of the scale was assessed using confirmatory factor analysis. The scale's reliability was evaluated using parallel forms reliability (Medication Adherence Report Scale-5), correlations with other scales (namely the Chronic Illness Self-Man-agement Scale – CISMS), Cronbach's alpha for internal consistency, and item-total score correlation coefficients.
Results: Confirmatory factor analysis validated the originally proposed three-factor structure of the scale. All model fit indices were within acceptable limits. A moderate and significant correlation was found with the Medication Adherence Report Scale used for parallel forms reliability (p<0.001). The total scale score showed significant correlations with all CISMS subscales (p<0.05). The Cronbach's alpha reliability coefficient for the total scale score was 0.70.

Conclusion: The Turkish version of the Medication Adherence Rating Scale, consisting of eight items (reduced from the original ten-item scale), has been shown to be a valid and reliable instrument.

Keywords: Chronic diseases, medication adherence, reliability, Turkish, validity