Determining Real Change in Conditioned Pain Modulation: A Repeated Measures Study in Healthy Volunteers - 01/09/20
, Harriet I. Kemp ⁎, 1, Chenxian Wu †, Deborah A. Ridout ‡, Andrew S.C. Rice ⁎Highlights |
• | Reporting in conditioned pain modulation (CPM) is not standardized and does not consider measurement error. |
• | A distribution-based approach enables the identification of “real” change in CPM. |
• | The proportion of CPM inhibitors and facilitators is paradigm dependent. |
• | Intersession CPM response is not consistent in healthy subjects. |
• | Standardization in reporting will underpin emerging clinical utility of CPM. |
Abstract |
Conditioned pain modulation (CPM) is a potentially useful biomarker in pain populations; however, a statistically robust interpretation of change scores is required. Currently, reporting of CPM does not consider measurement error. Hence, the magnitude of change representing a “true” CPM effect is unknown. This study determined the standard error of measurement (SEM) and proportion of healthy participants showing a “true” CPM effect with a standard CPM paradigm. Fifty healthy volunteers participated in an intersession reliability study using pressure pain threshold (PPT) test stimulus and contact heat, cold water, and sham conditioning stimuli. Baseline PPTs were used to calculate SEM and >±2 × SEM to determine CPM effect. SEM for PPT was .21 kg/cm2. An inhibitory CPM effect (>+2 SEM) was elicited in 59% of subjects in response to cold stimulus; in 44% to heat. Intrasession and intersession reliability of within-subject CPM response was poor (kappa coefficient <.36). Measurement error is important in determining CPM effect and change over time. Even when using reliable test stimuli, and incorporating measures to limit bias and error, CPM intersession reliability was fair and demonstrated a large degree of within-subject variation. Determining “true” change in CPM will underpin future interrogations of intraindividual differences in CPM.
Perspective |
This study used a distribution-based statistical approach to identify real change in CPM, based on the SEM for the test stimulus. Healthy volunteers demonstrate substantial within-subject variation; CPM effect was paradigm dependent at intrasession testing and unstable to the same paradigm at intersession testing.
Le texte complet de cet article est disponible en PDF.Key Words : Conditioned pain modulation, pressure pain threshold, measurement error, intersession test stability
Plan
| Disclosures: H.I.K was funded by a European Commission, NeuroPain FP7 Grant EC (#2013-602891). D.L.K.’s work was funded by a National Institute for Health Research (NIHR) and Health Education England (HEE) Clinical Doctoral Research Fellowship (CDRF 2013-04-009). D.R. has received financial support from the NIHR and HEE for her contribution to this work. Professor A.S.C.R. received financial support from DOLORisk, a European Union Horizon 2020 research and innovation programme (grant 633491) for his contribution to this manuscript. Study sponsors provided financial support for the conduct and reporting of this research, they did not contribute to study design; nor collection, analysis or interpretation of data; in the writing of this report; nor in the decision to submit the article for publication. |
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| Conflict of Interests: H.I.K., D.L.K., C.W., D.A.R.—none declared; A.S.C.R.—conflicts of interest occurring in last 24 months: • Orion Pharma funding; • Consultancy and advisory board work for Imperial College Consultants including remunerated work for: Pharmanovo, Galapagos, Toray, Quartet, Lateral, Novartis, Pharmaleads, Orion, Asahi Kasei & Theranexis; • Owner of share options in Spinifex Pharmaceuticals from which personal benefit accrued upon the acquisition of Spinifex by Novartis in July 2015 and from which future milestone payments may occur. Inventor on patents; • A.S.C.R., Vandevoorde S. and Lambert D.M. Methods using N-(2-propenyl) hexadecanamide and related amides to relieve pain. WO 2005/079771; • Okuse K. et al Methods of treating pain by inhibition of vgf activity EP13702262.0/ WO2013 110945. |
Vol 21 - N° 5-6
P. 708-721 - mai 2020 Retour au numéro
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