Measurement properties of the Swedish clinical outcomes in routine evaluation outcome measures (CORE-OM): Rasch analysis and short version for depressed and anxious out-patients in a multicultural area

Louise Danielsson; Magnus L Elfström; Javier Galan Henche; Jeanette Melin

doi:10.1186/s12955-022-01937-7

Measurement properties of the Swedish clinical outcomes in routine evaluation outcome measures (CORE-OM): Rasch analysis and short version for depressed and anxious out-patients in a multicultural area

Health Qual Life Outcomes. 2022 Feb 19;20(1):30. doi: 10.1186/s12955-022-01937-7.

Authors

Louise Danielsson^{1

2}, Magnus L Elfström³, Javier Galan Henche⁴, Jeanette Melin⁵

Affiliations

¹ Institute of Neuroscience and Physiology, Department of Health and Rehabilitation, Sahlgrenska Academy, University of Gothenburg, Box 455, 405 30, Gothenburg, Sweden. louise.danielsson@gu.se.
² Angered Hospital, Box 63, 422 24, Gothenburg, Sweden. louise.danielsson@gu.se.
³ Division of Psychology, School of Health, Care and Social Welfare, Mälardalen University, Eskilstuna, Sweden.
⁴ Angered Hospital, Box 63, 422 24, Gothenburg, Sweden.
⁵ RISE Metrology, Research Institutes of Sweden, Gothenburg, Sweden.

Abstract

Introduction: The Swedish version of the patient-reported Clinical Outcomes in Routine Evaluation Outcome Measures (CORE-OM) has demonstrated high reliability and acceptable convergent validity in explanatory factor analyses. However, the fundamental scale properties have not yet been validated according to item response theory. The aim of this study was to analyze the measurement properties of the Swedish CORE-OM in a cohort of psychiatric out-patients with depression and anxiety in a multicultural area and to explore combinations of items based on shorter versions of the scale (CORE-10, CORE-6D) to improve measurement properties.

Methods: Data from CORE-OM assessments of 337 patients were analyzed using Rasch analysis. The patients had a mean age of 30 ± 14 years, the majority were women (72%). Requirements for measurement properties were checked: overall model fit, item fit residuals, targeting, internal consistency, differential item functioning and thresholds. Sensitivity to change was also analyzed.

Results: The CORE-OM showed high internal consistency (person separation index = 0.947) and adequate targeting, but there was overall model misfit (item trait interaction χ² = 917.53, p < 0.001), indication of local dependency, and differential item functioning in 9 items. The risk items showed problems with disordered thresholds. The emotional component of the shorter CORE-6D showed the best fit for our sample. Adding 3 items to include depressive and trauma-related content resulted in a unidimensional 8-item set with acceptable reliability, model fit, targeting and sensitivity to change.

Conclusion: For out-patients with diagnosed depression or anxiety in a multicultural area, the Swedish CORE-OM showed high internal consistency, but also validity problems. Based on the shorter CORE-6D version, a unidimensional 8-item set could be an alternative brief measure of psychological distress for this population, but further validity studies are required. Qualitative studies exploring the CORE-OM items in non-native speakers are also warranted.

Keywords: Internal validity; Item response theory; Patient-reported outcome measures; Psychometrics.

MeSH terms

Adolescent
Adult
Anxiety / diagnosis
Female
Humans
Male
Outcome Assessment, Health Care
Outpatients*
Psychometrics / methods
Quality of Life*
Reproducibility of Results
Surveys and Questionnaires
Sweden
Young Adult