Cross-validation of the Depression, Anxiety, and Positive Outlook Scale (DAPOS) for Clinical Use Patricia Olaya-Contreras, RN,* Jorma Styf, MD,* Mari Lundberg, PhD,* and Bengt Jansson, PhDw Objective: The 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. Methods: A 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. Results: Internal 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. Discussion: To 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. Key Words: anxiety, depression, positive outlook, measurement invariance, psychometric, cross-cultural validity (Clin J Pain 2011;27:330–337) I n accordance with the recommendations to study pain from a biopsychosocial perspective, psychological factors have been established as crucial in the understanding of chronic musculoskeletal pain. 1 In recent years emotional factors, also known as mood factors, such as anxiety and depression have been shown to be salient predictors of pain disability in a chronic pain population, even more predictive than biomedical status and pain intensity factors. 1,2 The above standing facts have resulted in an increased interest for clinicians, other than psychologists, to understand and to screen for emotional factors that might influence the treatment outcome. Hence, there is a need to extend the knowledge and understanding of emotional factors into a more somatic context. The relationship between persistent pain and depres- sion is a well-known phenomenon, 3 as is the connection between anxiety and pain. 4–6 Anxiety and depression are both constructs that reflect a negative affect, but even though they often co-occur they are to be viewed as separate constructs. 7,8 In contrast, the hypothesis that happy mood, that is positive affect, can significantly reduce pain perception and increases pain tolerance has been demonstrated and it may certainly contribute in the management of chronic musculoskeletal pain. 9,10 Researchers and clinicians evaluating mood have a variety of options. 11 Most of the questionnaires used to assess depression and anxiety have been shortened to make them more user friendly but still, showing reliability and validity consistent with the original versions. 12–14 Measur- ing depression and anxiety as conceptually separate constructs has been difficult owing to the overlapping nature of the symptoms. 11 Moreover, assessment instru- ments typically only measure one construct at a time. In a clinical setting, it is especially important that the assessment and screening tools are brief. Another issue with the existing assessment instruments is that they are not designed for nonpsychiatric populations, 15,16 such as patients with musculoskeletal pain in an out patient setting. The Depression, Anxiety, and Positive outlook Scale (DAPOS) was developed to address the shortcomings of previous questionnaires in assessing negative and positive affect in pain populations. 17 The initial validation study of DAPOS suggests that the psychometric properties have been preserved, as a brief tool for assessing mood in patients with chronic pain. 17 DAPOS was further tested with regard to responsiveness and construct vali- dity in patients with chronic pain before and after a multidisciplinary intervention, they reported excellent construct validity and acceptable responsiveness. 18 How- ever, DAPOS has neither been tested in, other contexts, that is, other orthopedic populations or languages, nor do we know if DAPOS is stable across sex or pain localization. The main purpose of this study was to investigate the different psychometric properties of the Swedish version of DAPOS across sex and diagnostic groups in a large orthopedic population. A contributory objective was to perform a cross-cultural adaptation of the DAPOS in the Swedish language. Copyright r 2011 by Lippincott Williams & Wilkins Received for publication June 9, 2010; revised October 8, 2010; accepted October 15, 2010. From the *Department of Orthopedics, Sahlgrenska Academy; and wDepartment of Psychology, University of Gothenburg, Gothen- burg, Sweden. Reprints: Patricia Olaya-Contreras, RN, Division of Occupational Orthopedics, Sahlgrenska University Hospital, Per Dubbsgatan 14, S-413 46 Gothenburg, Sweden (e-mail: patricia.olaya@orthop.gu.se). ORIGINAL ARTICLE 330 | www.clinicalpain.com Clin J Pain  Volume 27, Number 4, May 2011