The Central Aspects of Pain in the Knee (CAP-Knee) questionnaire; a mixed-methods study of a self-report instrument for assessing central mechanisms in people with knee pain

Akin-Akinyosoye, Kehinde; James, Richard J E; Mcwilliams, Daniel F; Millar, Bonnie; Das Nair, Roshan; Ferguson, Eamonn; Walsh, David A

Abstract

OBJECTIVES: Pain is the prevailing symptom of knee osteoarthritis. Central sensitisation creates discordance between pain and joint pathology. We previously reported a central pain mechanisms trait derived from 8 discrete characteristics: neuropathic-like pain, fatigue, cognitive-impact, catastrophising, anxiety, sleep disturbance, depression, and pain distribution. We here validate and show that an 8-item questionnaire, Central Aspects of Pain in the Knee (CAP-Knee) is associated both with sensory and affective components of knee pain severity.
METHODS: Participants with knee pain were recruited from the Investigating Musculoskeletal Health and Wellbeing study in the East Midlands, UK. CAP-Knee items were refined following cognitive interviews. Psychometric properties were assessed in 250 participants using Rasch-, and factor-analysis, and Cronbach’s alpha. Intra-class correlation coefficients tested repeatability. Associations between CAP-Knee and McGill Pain questionnaire pain severity scores using linear regression.
RESULTS: CAP-Knee targeted the knee pain sample well. Cognitive interviews indicated that participants interpreted CAP-Knee items in diverse ways aligned to their intended meanings. Fit to the Rasch model was optimised by rescoring each item, producing a summated score from 0-16. Internal consistency was acceptable (Cronbach’s alpha=0.74) and test–retest reliability excellent (ICC2,1=0.91). Each CAP-Knee item contributed uniquely to one discrete `Central Mechanisms trait’ factor. High CAP-Knee scores were associated with worse overall knee pain intensity and with each of sensory and affective McGill Pain Questionnaire scores.
CONCLUSION: CAP-Knee is a simple and valid self-report questionnaire, which measures a single `Central Mechanisms’ trait, and may help identify and target centrally-acting treatments aiming to reduce the burden of knee pain.

Citation

Akin-Akinyosoye, K., James, R. J. E., Mcwilliams, D. F., Millar, B., Das Nair, R., Ferguson, E., & Walsh, D. A. (2021). The Central Aspects of Pain in the Knee (CAP-Knee) questionnaire; a mixed-methods study of a self-report instrument for assessing central mechanisms in people with knee pain. Osteoarthritis and Cartilage, 29(6), 802-814. https://doi.org/10.1016/j.joca.2021.02.562

• Journal Article Type: Article
• Acceptance Date: Feb 16, 2021
• Online Publication Date: Feb 20, 2021
• Publication Date: 2021-06
• Deposit Date: Feb 24, 2021
• Publicly Available Date: Feb 21, 2022
• Journal: Osteoarthritis and Cartilage
• Print ISSN: 1063-4584
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 29
• Issue: 6
• Pages: 802-814
• DOI: https://doi.org/10.1016/j.joca.2021.02.562
• Keywords: Rheumatology; Orthopedics and Sports Medicine; Biomedical Engineering
• Public URL: https://nottingham-repository.worktribe.com/output/5348283