Validity and reliability of the Norwegian version of the Musculoskeletal Health Questionnaire in people on sick leave

Background The Musculoskeletal Health Questionnaire (MSK-HQ) is a recently developed generic questionnaire that consists of 14 items assessing health status in people with musculoskeletal disorders. The objective was to translate and cross-culturally adapt the MSK-HQ into Norwegian and to examine its construct validity and reliability in people on sick leave with musculoskeletal disorders. Methods A prospective cohort study was carried out in Norway on people between 18 and 67 years of age and sick leave due to a musculoskeletal disorder. The participants were recruited through the Norwegian Labour and Welfare Administration during November 2018-January 2019 and responded to the MSK-HQ at inclusion and after four weeks. Internal consistency was assessed by Cronbach's alpha, and structural validity with a factor analysis. Construct validity was assessed by eight "a priori" defined hypotheses regarding correlations between the MSK-HQ and other reference scales. Correlations were analyzed by Spearman's- or Pearson's correlation coefficient and interpreted as high with values >= 0.50, moderate between 0.30-0.49, and low < 0.29. Reliability was tested with test-retest, standard error of measurement (SEM) and smallest detectable change (SDC). Results A total of 549 patients, mean age (SD) 48.6 (10.7), 309 women (56.3%), were included. The mean (SD) MSK-HQ sum scores (min-max 3-56) were 27.7 (8.2). Internal consistency was 0.86 and a three-factor structure was determined by factor analysis. Construct validity was supported by the confirmation of all hypotheses; high correlation with HRQOL, psychosocial risk profile, and self-perceived health; moderate correlation with physical activity, self-perceived work ability, and work presenteeism; and low correlation with the number of sick days. The test-retest reliability was good with an intraclass correlation coefficient of 0.83 (95% CI, 0.74-0.89), SEM was 2.3 and SDC 6.5. Conclusions The Norwegian version of the MSK-HQ demonstrated high internal consistency, a three-factor structure, good construct validity and good test-retest reliability when used among people on sick leave due to musculoskeletal disorders.