Factors Associated with Low Inter-Session Reliability of Conditioned Pain Modulation in Older People with or Without Chronic Musculoskeletal Pain

Hironobu Uzawa; Hideaki Ishii; Takeki Ishida; Takashi Shida; Hiroto Furuyama; Yusuke Nishida

doi:10.2147/JPR.S391943

Factors Associated with Low Inter-Session Reliability of Conditioned Pain Modulation in Older People with or Without Chronic Musculoskeletal Pain

J Pain Res. 2023 Mar 23:16:1039-1053. doi: 10.2147/JPR.S391943. eCollection 2023.

Authors

Hironobu Uzawa¹, Hideaki Ishii¹, Takeki Ishida¹, Takashi Shida^{2

3}, Hiroto Furuyama⁴, Yusuke Nishida¹

Affiliations

¹ Department of Physical Therapy, International University of Health and Welfare, Narita, Chiba, Japan.
² Department of Medical Technology and Science, International University of Health and Welfare, Narita, Chiba, Japan.
³ Research Team for Promoting Independence and Mental Health, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, Japan.
⁴ Department of Rehabilitation, International University of Health and Welfare Narita Hospital, Narita, Chiba, Japan.

Abstract

Purpose: Conditioned pain modulation (CPM) is a measurement of the descending pain pathways that inhibit or facilitate afferent noxious stimuli. The reliability of CPM in older individuals with or without chronic musculoskeletal pain has not been sufficiently reported. This study aimed to examine the inter-session reliability of CPM in these cohorts and the factors in CPM reliability.

Patients and methods: Individuals aged 65 or older were recruited in Narita, Japan. The measurements were performed on separate days 2 weeks apart (sessions 1 and 2). Each participant's hand was immersed in cold water, and we measured pressure pain threshold (PPT) before and after the immersion. The ratio before and after PPT measurements was presented as CPM index. The autonomic activities (heart rate variability, heart rate, and blood pressure) were simultaneously measured. An absolute reliability of CPM index was analyzed by the adjusted two-way analysis of variance (ANOVA) and the Bland Altman plot, and relative reliability was analyzed by intraclass correlation coefficient (ICC). Spearman's rho correlation and the adjusted multivariate regression analysis were utilized for examining the CPM reliability factors.

Results: Thirty-two participants were divided into two groups: chronic pain (n=19) and non-chronic pain (n=13) groups. The mean difference between session 1 and 2 in CPM index showed a systematic error in the chronic pain group at 17.3 (confidence interval, CI: 15.0 to 19.7), but none in the non-chronic pain group at 3.7 (CI: -0.02 to 7.4). The adjusted two-way ANOVA for CPM index did not identify any differences. ICC was not significant at p=-0.247 in the non-chronic and 0.167 in chronic pain. Multivariate regression analysis revealed total power and low/high frequencies as significant factors for CPM index.

Conclusion: This study identified low inter-session reliability in older adults with chronic musculoskeletal pain and autonomic nervous system activities as factors in CPM reliability.

Keywords: autonomic nervous system; chronic musculoskeletal pain; conditioned pain modulation; inter-session reliability; older people.

Grants and funding

This research was funded by the JSPS Grants-in-Aid for Scientific Research, Challenging Research, Explorator (21K19733). The funders had no role in any of the procedures in this study.