The factor structure of 36-Item Short Form Survey among patients with type 2 diabetes

BACKGROUND: Quality of life is one of the most important issues in patients with type 2 diabetes mellitus (T2DM). Although some studies examined the quality of life in these patients, most of them are related to descriptive statistics. It is essential to address measurement assessment to assess the quality of life among patients with T2DM. Therefore, this study aimed to examine the factor structure of the 36-Item Short Form Survey (SF-36) among patients with T2DM. METHODS: This study was conducted using convenience sampling in Tehran and Mashhad, Iran, from 2019 to 2020. In this psychometric study, the SF-36, according to Kline's approach, was administered among 290 patients with T2DM. The factor structure of the scales was assessed. To examine factor structure, we examined exploratory and confirmatory factor analysis. Besides, the reliability of the questionnaire was assessed via Cronbach's alpha and split-half. In sum, to analyze the data, SPSS software was used. RESULTS: By examining the Promax matrix, the SF-36 resulted in a six-factor structure; however, the items of one of the factors were removed due to cross-loading (0.51-0.53). According to the findings of exploratory factor analysis in 5 factors, Cronbach's alpha coefficients ranged from 0.73 to 0.97 and split-half ranged from 0.60 to 0.97. CONCLUSION: The findings revealed that the five-factor model of the SF-36 had satisfactory validity and reliability. Thus, this questionnaire can be used in future studies to assess the quality of life of patients with T2DM.