Validation of the RAND 36-Item Health Survey questionnaire in Brazil

Abstract

Background: Health-related quality of life is frequently used as an outcome measure that improves the quality of care. The SF-36 and RAND-36 were derived from the Medical Outcomes Study. Objective The present study aimed to validate the RAND-36 in Brazil, in healthy individuals and patients with liver disease. Methods: Confirmatory factor analysis (CFA) was conducted by using JASP Software. The parameters of the items were estimated using the Robust Diagonally Weighted Least Squares (RDWLS) approach. Comparative fit index (CFI), Goodness-of-fit index (GFI), Tucker-Lewis Index (TLI) and the root mean square error of approximation (RMSEA) were evaluated. Internal consistency was measured using the Composite reliability index. Convergent validity between RAND-36 domains and Work Ability Index (WAI) was conducted. Results: This validation study included 763 individuals, 400 (52.4%) with chronic liver disease. The most prevalent liver diseases were hepatitis C (13.9%), alcoholic liver disease (11.8%), and steatosis (12.1%). The measurement model tested using the CFA obtained the following adjustment indicators: X2 (df): 599.65 (498); CFI: 0.998; GFI: 0.998; TLI: 0.998; RMSEA: 0.016 (90%CI: 0.011-.021). Convergent validity of RAND-36 and total WAI ranged from medium to large correlation. Conclusion: The RAND-36 is effective in measuring the perception of health-related quality of life in individuals with and without chronic liver disease. The results of our study support the developer’s claims for the reliability of the RAND-36 version 1 as a measure of health-related quality of life. The evidence for the construct validity of the RAND-36 was substantial.