Evaluating the construct validity and internal consistency of the Sickness Questionnaire in a Swedish sample of adults with longstanding pain

Jenny Åström; Linda Holmström; Bianka Karshikoff; Anna Andreasson; Mike K Kemani

doi:10.1515/sjpain-2021-0070

Evaluating the construct validity and internal consistency of the Sickness Questionnaire in a Swedish sample of adults with longstanding pain

Scand J Pain. 2021 Dec 19;22(1):88-96. doi: 10.1515/sjpain-2021-0070. Print 2022 Jan 27.

Authors

Jenny Åström^{1

2}, Linda Holmström^{1

2

3}, Bianka Karshikoff^{2

4}, Anna Andreasson^{5

6

7}, Mike K Kemani^{1

5}

Affiliations

¹ Theme Women's Health and Allied Health Professionals, Medical Unit Medical Psychology, Karolinska University Hospital, Stockholm, Sweden.
² Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
³ Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden.
⁴ Department of Social Studies, University of Stavanger, Stavanger, Norway.
⁵ Stress Research Institute, Stockholm University, Stockholm, Sweden.
⁶ Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.
⁷ Department of Psychology, Macquarie University, Macquarie Park, NSW, Australia.

PMID: 34931508
DOI: 10.1515/sjpain-2021-0070

Abstract

Objectives: Low-grade inflammation is a possible contributing factor in the development and persistence of chronic primary pain syndromes. Related to inflammatory activity is sickness behavior, a set of behavioral responses including increased pain sensitivity, fatigue, malaise, fever, loss of appetite, as well as depressive behavior and anhedonia. To capture these behavioral responses and their relation to longstanding pain, psychometrically sound self-report questionnaires are needed. The Sickness Questionnaire (SicknessQ) was developed to assess self-reported sickness behavior based on studies on acute immune activation while maintaining relevance for persistent conditions. The aim of the current study was to evaluate aspects of the validity and reliability of the SicknessQ in a Swedish sample of persons with longstanding pain.

Methods: Aspects of construct validity were evaluated by means of performing a confirmatory factor analysis (CFA) (testing structural validity) and by relevant hypothesis testing i.e., that ratings of sickness behavior in combination with other related factors (e.g., depression and anxiety) would be significantly related to ratings of avoidance. Reliability was evaluated by means of analyzing the internal consistency of items.

Results: Following the CFA, a non-significant Chi-Square test (χ² [32, N=190] = 42.95, p=0.094) indicated perfect model fit. Also, the relative fit indices supported adequate model fit (CFI = 0.978; TLI = 0.969; RMSEA = 0.0430). Sickness behavior (p<0.0001), depression (p<0.05) and pain duration (p<0.05) significantly contributed to the regression model, explaining 45% of the total variance in avoidance. Internal consistency was adequate, as indicated by a Cronbach's α value of 0.82 for the entire questionnaire.

Conclusions: Results indicate that the SicknessQ has adequate structural validity as well as adequate internal consistency, and is significantly associated with avoidance. The SicknessQ appears to have utility as a self-report questionnaire to assess symptoms of sickness behavior for adults with longstanding pain.

Keywords: Sickness Questionnaire (SicknessQ); avoidance; longstanding pain; reliability; sickness behavior; validity.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adult
Chronic Pain*
Humans
Psychometrics
Reproducibility of Results
Surveys and Questionnaires
Sweden