Development and validation of medication literacy scale for adults: MELSA version II

Abstract

Abstract Background The Medication Literacy Scale for Adults (MELSA) version I was previously developed among adults with high educational levels. However, the validity of the tool for the general populations was not established. Objective The aim of the study was to develop and evaluate the psychometric properties of the MELSA version II among community-dwelling Turkish adults with both low and high education levels. Methods After the item development and content and face validity testing, test-retest reliability, explanatory factor analysis (EFA), confirmatory factor analysis (CFA), internal consistency, item response theory approach (Rasch analysis), and hypothesis testing were carried out. Results The interclass correlation coefficient (agreement) was 0.753 between the test and the two weeks retest. Kuder Richardson-20 was 0.89 with a unidimensional structure, according to EFA, CFA, and Rasch analysis. Rasch analysis indicated the person reliability of the 9-item MELSA version II as 0.74. Participants with a high education level and a high level of self-reported reading ability for health-related information had a higher score on MELSA version II (p < 0.05). Conclusion The 9-item MELSA version II is a web-based scale that is brief, valid, and easy to administer in person using an mobile device. It could be used in different countries and populations after conducting appropriate translation and cultural adaptation.

Keywords

• Medication literacy
• Rasch
• Factor analysis
• Psychometrics
• Validity and reliability
• Item response theory