Background & Aims
The Central Aspects of Pain in the Knee (CAP-Knee) questionnaire was developed as a measure of central augmented pain in individuals with knee pain1-3. It comprises 8 items (fatigue, anxiety, depression, pain distribution, catastrophising, sleep disturbance, neuropathic-like pain, and cognitive impact). CAP-Knee demonstrated good internal validity, is positively associated with pain severity, and more closely correlated with quantitative sensory testing (QST) evidence of central sensitisation (pressure pain detection threshold (PPT) distal to the affected joint) than were measures of any single associated clinical characteristic (e.g., anxiety)1-3. The CAP questionnaire was generalised from “knee” to “joint” in discussions with patients to extend its use beyond knee pain. This study aimed to assess if CAP represents a unitary factor associated with pain and QST evidence of central augmented pain in individuals with rheumatoid arthritis (RA).
Methods
Individuals with RA with pain >3/10 were recruited from Nottinghamshire NHS Trusts and Investigating Musculoskeletal Health and Wellbeing Database4. CAP and pain data were included from PUMIA, Branch (KCL) and SOCRATES (Cardiff) studies. A subgroup of participants completed QST and questionnaires (Hospital Anxiety and Depression Scale, Pain Catastrophising, Athens Insomnia Scale, Bristol Rheumatoid Arthritis Fatigue Scale, Cognitive Failures Questionnaire, Widespread Pain Index, painDETECT). QST was assessed in the following sequence: PPT at the medial joint line of the most painful knee, tibialis anterior and contralateral brachioradialis, Temporal Summation (TS) at rectus femoris of the most painful knee, and Conditioned Pain Modulation (CPM), with ischaemic arm pain conditioning and PPT at tibialis anterior. Cronbach alpha, confirmatory factor analysis (CFA), Rasch measurement theory (RMT) analysis and correlation coefficients assessed CAP validity and reliability.
Results
380 people with RA were recruited (221 Nottingham, 107 KCL, 52 Cardiff). Participants were (median (IQR)) 63y (54 to 72), 278 (73%) females, with `pain now’ levels of 5 (3 to 7), `strongest pain’ 8 (5 to 9) and `average pain’ 6 (5 to 8) over the past week, and CAP scores 9 (6 to 11). CAP items correlated with each other 0.11?r?0.67. CFA demonstrated good model fit with all items loading to a single factor (CFI=0.99, TLI=0.99, RMSEA=0.034, SRMR=0.03). RMT analysis displayed no local item dependency. Depression and pain distribution items showed some misfit. Optimal scoring algorithm (0-2) Cronbach’s alpha (0.82) indicated good internal consistency. CAP correlated moderately with pain (now, strongest, average, PainDETECT: 0.49??? 0.55), and weakly with QST (0.12???0.05). CAP scores correlated moderately to strongly with questionnaires representing each item 0.43???0.76, there was no difference when item relating to the questionnaire were removed from the calculation of CAP 0.43???0.76.
Conclusions
The CAP questionnaire in individuals with RA demonstrated good construct and structural validity, and internal consistency. The original scoring schemes validated for CAP-knee also provided optimal fit to the Rasch measurement model for CAP, which was not improved by removing the pain distribution item. The adaption of the CAP-Knee questionnaire from knee-specific questions to generic “joint” enables use in other painful conditions. The simple and valid questionnaire measures a unidimensional construct linked to key characteristics of centrally augmented pain that were not captured by the included QST modalities. This questionnaire measures a key factor of centrally augmented pain.
References
1.Akin-Akinyosoye K, Frowd N, Marshall L, Stocks J, Fernandes GS, Valdes A, et al. Traits associated with central pain augmentation in the Knee Pain In the Community (KPIC) cohort. Pain 2018; 159: 1035-1044.
2.Akin-Akinyosoye K, James RJE, McWilliams DF, Millar B, das Nair R, Ferguson E, et al. 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 Cartilage 2021; 29: 802-814.
3.Akin-Akinyosoye K, Sarmanova A, Fernandes GS, Frowd N, Swaithes L, Stocks J, et al. Baseline self-report ‘central mechanisms’ trait predicts persistent knee pain in the Knee Pain in the Community (KPIC) cohort. Osteoarthritis Cartilage 2020; 28: 173-181.
4.Millar B, McWilliams DF, Abhishek A, Akin-Akinyosoye K, Auer DP, Chapman V, et al. Investigating musculoskeletal health and wellbeing; a cohort study protocol. BMC Musculoskeletal Disorders 2020; 21: 182.
Presenting Author
Stephanie Smith
Poster Authors
Stephanie Smith
PhD
University of Nottingham, Pain Centre Versus Arthritis
Lead Author
Vasileios Georgopoulos
The University of Nottingham
Lead Author
Onosi Ifesemen
MPH
Pain Centre Versus Arthritis, APDP, Academic Rheumatology, University of Nottingham
Lead Author
Richard James
PhD
School of Psychology, University of Nottingham, UK
Lead Author
Eamonn Ferguson
PhD
School of Psychology, University of Nottingham, UK
Lead Author
Richard Wakefield
BM
Leeds Institute of Rheumatic and Musculoskeletal Medicine, and NIHR Leeds Biomedical Research Centre
Lead Author
Deborah Wilson
Rheumatology, Sherwood Forest Hospitals NHS Foundation Trust, Nottinghamshire, UK
Lead Author
Philip Buckley
Rheumatology, Sherwood Forest Hospitals NHS Foundation Trust, Nottinghamshire, UK
Lead Author
Dorothy Platts
Independent Consultant, Nottingham, UK
Lead Author
Suzan Ledbury
Independent Consultant, Nottingham, UK
Lead Author
Ernest Choy
PhD
School of Medicine, University of Cardiff, Cardiff, UK
Lead Author
Timothy Pickles
School of Medicine, University of Cardiff, Cardiff, UK
Lead Author
Zoe Rutter-Locher
Faculty of Life Sciences and Medicine, Kings College London, UK
Lead Author
Daniel McWilliams
PhD
School of Medicine, University of Nottingham
Lead Author
David Walsh
MD
School of Medicine, University of Nottingham
Lead Author
Topics
- Assessment and Diagnosis