TRANSLATION AND PERFORMANCE OF THE NORWEGIAN SF-36 HEALTH SURVEY IN PATIENTS WITH RHEUMATOID-ARTHRITIS - I - DATA QUALITY, SCALING ASSUMPTIONS, RELIABILITY, AND CONSTRUCT-VALIDITY

The SF-36 was translated into Norwegian following the procedures devel oped by the International Quality of Life Assessment (IQOLA) Project. To test for the appropriateness of the Norwegian Version 1.1 of the SF -36 in patients with rheumatoid arthritis (RA), 1552 RA patients were mailed the form. Psychometric methods used in previous U.S. and Swedis h studies were replicated. The response rate was 66%. The sample (mean age 62 years, mean disease duration 13 years) was over-represented by females (79%). Totally, 74% of the questionnaires were complete. Miss ing value rates per item ranged from 0.4% to 9.0% (mean 4.2%). In the Role-Emotional scale, all three items had missing value rates above av erage and higher than reported in the U.S. and Swedish studies. Tests of scaling assumptions confirmed the hypothesized structure of the que stionnaire, but results were suboptimal in the General Health scale. I n all scales the Cronbach's alphas exceeded the 0.70 standard for grou p comparisons. In the Physical Functioning scale, Cronbach's alpha exc eeded the 0.90 standard for individual comparisons. There was good evi dence for the construct validity of the questionnaire. Generally, the Norwegian SF-36 version 1.1 distributed to RA patients held the psycho metric properties found in other countries and in normal populations. The translations of items in the General Health and Role-Emotional sca les were reassessed. Minor deficiencies were detected and changed (SF- 36 Norwegian Version 1.2). (C) 1998 Elsevier Science Inc.