Original ArticleUse of Structural Equation Modeling to Test the Construct Validity of the SF-36 Health Survey in Ten Countries: Results from the IQOLA Project
Introduction
The measurement of health status begins with a model of health that determines the content of a questionnaire and serves as the “blueprint” for scoring multi-item scales and summary measures. This model also provides a confirmatory strategy for evaluating the construct validity of a questionnaire. The reproducibility of such models, an issue of much debate in the international literature (see, for example, 1, 2, 3, 4), is a crucial prerequisite to the scoring and interpretation of a questionnaire in multinational comparisons of health and trials of treatment effectiveness. To date, such comparisons have been hampered by a lack of standardization of questionnaire content across nations [5] and a lack of systematic, comprehensive approaches to the validation of translations of health status measures 6, 7. The International Quality of Life Assessment (IQOLA) Project translated the SF-36 Health Survey to test the feasibility of standardizing comparisons of health across countries [8].
Reported here are the results of the use of structural equation modelling (SEM) to test the cross-cultural construct validity of the SF-36 by comparing its factor structure across ten IQOLA countries, including Denmark, France, Germany, Italy, the Netherlands, Norway, Spain, Sweden, the United Kingdom, and the United States. Confirmatory factor analysis (CFA) has been used to support the cross-cultural construct validity of measures used in psychology and education (e.g., 9, 10, 11, 12), health care utilization [13], epidemiology [14], and physical [15] and mental health status [16]. However, we know of no other instance where this method has been applied to test the cross-cultural construct validity of a comprehensive, generic model of health status or where it has been applied to evaluate the similarity of questionnaire structure across more than three different cultures. The analyses reported here provide information about the generalizability of the structure of health in ten nations differing in language, geography, and economic and political systems.
The basic question addressed in this research is whether a questionnaire designed as a generic measure of health status in one country can be translated with comparable validity. We hypothesized that the SF-36 model of the relationships of items to scales and scales to each other that fit the data in one country would be replicated in nine other countries sufficiently to warrant its use and interpretation in those countries. Based on the conceptual background of the content of the SF-36 [17] as well as the results of previous research in the United States 18, 19, 20, we hypothesized that a model with the following characteristics would fit SF-36 data: (1) the model would include eight first-order factors corresponding to the eight scales of the SF-36 (described below under Methods); (2) items used in scoring each scale would have stronger relationships with their corresponding first-order factors than with competing first-order factors; (3) second-order physical and mental factors would account for correlations among the eight scales; and (4) a single third-order health factor would account for the correlations among the second-order factors. We also tested the fit of models that added a third second-order factor as explained below.
Section snippets
Samples
Samples of respondents were drawn within each country according to methods specified in detail elsewhere 21, 22, 23, 24, 25. Nationally representative samples were selected in Denmark, France, Germany, Italy, Norway, Spain, and the United States. A supplemental sample of the elderly in France (N = 348) and respondents who required assistance completing the questionnaire in Italy (N = 548) were not included in the analysis. The Spanish data were limited to those patients who had complete data
First-Order Factor Structure
Figure 2 describes the pattern of relationships between the SF-36 items and the eight first-order factors. Dashed lines indicate secondary loadings that were consistently greater than 0.30 across countries. As summarized in Table 1, standardized regression coefficients to predict items from factors were approximately 0.40 or higher for each item with its hypothesized factor and lower with competing factors across countries. However, there were a few exceptions to this pattern.
The “vigorous
Discussion
These results support a model of relationships between SF-36 items and factors and factors to each other developed in the U.S. database, across databases from nine other countries. In general, results across ten countries confirmed the eight first-order factor structure of the SF-36. With few exceptions, standardized regression coefficients to predict items from factors were 0.40 or higher for each item with its hypothesized factor (demonstrating convergent validity) and lower with competing
References (65)
- et al.
Translation, validation and norming of the Dutch language version of the SF-36 Health Survey in community and chronic disease populations
J Clin Epidemiol
(1998) - et al.
The Swedish SF-36 Health Survey. IEvaluation of data quality, scaling assumptions, reliability, and construct validity across general populations in Sweden
Soc Sci Med
(1995) - et al.
Methods for validating and norming translations of health status questionnairesThe IQOLA Project approach
J Clin Epidemiol
(1998) - et al.
Tests of data quality, scaling assumptions, and reliability of the SF-36 in eleven countriesResults from the IQOLA Project
J Clin Epidemiol
(1998) - et al.
Translating health status questionnaires and evaluating their qualityThe IQOLA Project approach
J Clin Epidemiol
(1998) State of science 1986Quality of life and functional status as target variables for research
J Chronic Dis
(1987)- et al.
Comparisons of health-related attitudesA cross-national, factor analytic study
Soc Sci Med
(1971) The philosophy of health-related quality of life translation
Qual Life Res
(1993)- et al.
Cross-cultural comparability of quality of life measures
Br J Med Econ
(1992) - et al.
Culture, illness, and careClinical lessons from anthropologic and cross-cultural research
Ann Intern Med
(1978)
Quality of life assessment across cultures
Int J Ment Health
Critical review of the international assessments of health-related quality of life
Qual Life Res
Developing and evaluating cross-cultural instruments from minimum requirements to optimal models
Qual Life Res
The IQOLA Project Group. The SF-36 Health SurveyDevelopment and use in mental health research and the IQOLA Project
Int J Ment Health
The two-factor model of self-reported moodA cross-cultural replication
J Pers Assess
Convergent validity of the Spanish and English forms of the Strong-Campbell Interest Inventory for bilingual Hispanic high school students
J Coun Psychol
Confirmatory factor analyses of the Wechsler Intelligence Scale for children-revised and the Hong Kong–Wechsler Intelligence Scale for children
Educ Psychol Meas
The Academic Motivation ScaleA measure of intrinsic, extrinsic, and a motivation in education
Educ Psychol Meas
Cross-national comparative research on the utilization of medical services
Med Care
Comparative research in social epidemiologyMeasurement issues
Ethn Dis
The structure of self-reported physical health among the aged in the United States and Japan
Med Care
The structure of the mental health inventory among Chinese in Taiwan
Med Care
The MOS 36-Item Short-Form Health Survey (SF-36). IConceptual framework and item selection
Med Care
The MOS 36-Item Short-Form Health Survey (SF-36). IIPsychometric and clinical tests of validity in measuring physical and mental health constructs
Med Care
The MOS 36-Item Short-Form Health Survey (SF-36). IIITests of data quality, scaling assumptions and reliability across diverse patient groups
Med Care
Comparisons of the costs and quality of norms for the SF-36 Health Survey collected by mail versus telephone interviewResults from a national survey
Med Care
Valdating the SF-36 Health Survey QuestionnaireNew outcome measure for primary care
Br Med J
1990 National Survey of Functional Health StatusFinal Report
The structure of self-reported health in chronic disease patients
Psychol Assess
Conceptualization and Measurement of Health for Adults in the Health Insurance Study, Vol. VI, R-1987/6-HEW
SF-36 Health Survey Manual and Interpretation Guide
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