Background: Adaptation of a patient-reported outcomes survey into a new language requires careful translation procedures as well as qualitative and quantitative psychometric testing. This study aimed to evaluate the basic psychometric properties of the new Saudi Arabian SF-36v2 and establish norm data for Saudi Arabia.
Methods: Translation and adaptation of the SF-36v2 used standard methodology. Psychometric validation included two stages: 1) A qualitative study (n = 100) explored the components of health and health-related quality of life considered important in Saudi Arabia and evaluated the content validity of the SF-36v2 in Saudi Arabia, and 2) A quantitative study (n = 6166) evaluated the basic psychometric properties of the Saudi SF-36v2 and established norm data for Saudi Arabia. Comparison with US general population data (n = 4040) evaluated differential item function (DIF) and cross-national differences.
Results: The qualitative study supported the content validity of the Saudi SF-36v2. Cognitive debriefing identified only few and minor problems. Psychometric analyses supported item convergence within scales and differentiation across scales of the SF-36v2. Scale level exploratory factor analyses did not support the typical distinction between physical health and mental health components. Internal consistency reliability was satisfactory for all scales except the social function scale (alpha = 0.67). Cross-national DIF was identified for 9 items. In the Saudi general population, the average vitality score was lower for women (- 2.71 points) compared to men. For men, older age groups scored lower on the physical function scale (- 3.31) and the physical health component (- 3.06). For women, older age groups scored lower on the role physical (- 3.72), bodily pain (- 3.66), and vitality (- 2.32) scales as well as the physical health component (- 3.52). Compared to the 2009 United States general population, and after adjusting for age, gender, and differential item function, persons in Saudi Arabia had lower average scores for the physical function (- 3.10), role physical (- 4.75), social function (- 4.23), role emotional (- 5.67), and mental health (- 4.82) scales, as well as the mental health component (- 4.57).
Conclusion: This Saudi normative study of patient reported outcomes supported the validity and reliability of the new Saudi SF-36v2 and found cross-national differences with the USA.
Keywords: Norms; Population-based survey; Quality of life; SF-36v2; Saudi Arabia; Validity.