• Patricia Olaya-Contreras, Jorma Styf, Mari Lundberg, and Bengt Jansson.
• Department of Occupational Orthopedics, Sahlgrenska University Hospital, Per Dubbsgatan 14, Gothenburg, Sweden. patricia.olaya@orthop.gu.se
• Clin J Pain. 2011 May 1;27(4):330-7.

ObjectiveThe main objective of this study was to investigate different psychometric properties of the Swedish version of the Depression, Anxiety, and Positive Outlook Scale (DAPOS) in patients with chronic musculoskeletal pain in an orthopedic setting.MethodsA total of 449 participants took part in the study, including 288 patients with chronic musculoskeletal pain and 161 participants in a reference group. Internal consistency, convergent validity, and measurement invariance of the constructs of DAPOS were investigated across sex and diagnostic groups. The Beck Depression Inventory and the Spielberger Anxiety Inventory were used for measures of convergent validity. Multigroup confirmatory factor analysis was performed to test measurement invariance of the theoretical constructs of DAPOS.ResultsInternal consistency was good for all 3 constructs, and correlations concerned with convergent validity were found to be acceptable to good. With regard to cross-validation, the 3 constructs of DAPOS were strictly measurement invariant with respect to sex. Across diagnostic groups, the constructs of anxiety and positive outlook were almost strictly measurement invariant, although there were some restrictions of measurement invariance for the construct of depression.DiscussionTo be able to rely on an instrument with as few items as DAPOS, the cross-validation of its constructs for sex and diagnostic groups is a valuable information, particularly when investigated in patients with musculoskeletal pain. Based on these results, we recommend that DAPOS could replace longer and more time-consuming screening tests in clinical settings.

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