669: Validity and Reliability of Conditioned Modulation of Pain Unpleasantness

Topic: Experimental (Non-clinical) Human Studies
Subtopic: Non -specific to any diagnosis, Quantitative Sensory testing (static and dynamic, e.g., HPT, PPT, CPM, TSP, offset analgesia)

Background and Aims: Conditioned pain modulation (CPM) is commonly used to assess endogenous analgesia, with most paradigms emphasizing the sensory–discriminative dimension of pain. However, modulation of the affective dimension may provide complementary information, as pain intensity and unpleasantness, although related, do not necessarily converge. Incorporating affective outcomes may therefore refine the assessment of endogenous pain inhibition. This study aimed to examine the validity and reliability of CPM applied to the affective dimension of pain and to explore whether repeated measurements influence the psychometric properties of this paradigm.

Methods: Thirty-two healthy participants were evaluated using a sequential CPM. Pain intensity and unpleasantness of the test stimulus (TS) were assessed in randomized order, which consisted of 4kg pressure applied to the anterior temporalis. The conditioning stimulus was hand immersion in ice water. This paradigm was repeated three times (1-minute interval). During the first repetition, the unconditioned TS was assessed twice (5-minute interval) to estimate the standard error of measurement (SEM). After 45 minutes, the procedures were repeated, forming two identical blocks. Validity and reliability of CPM (arithmetic differences) were estimated using intraclass correlation coefficients, and agreement using the SEM.

Results: Participants had a mean (SD) age of 20.75 (2.48) years, with equal sex distribution. Validity between intensity- and unpleasantness-based CPM was fair in block 1 (ICC=0.48, p=0.002) and excellent in block 2 (ICC=0.78, p<0.001). Reliability was poor for single repetitions (intensity ICC=−0.06, unpleasantness ICC=0.21). SEM values indicated substantial variability in the changes required to exceed measurement error. When the average of three repetitions was considered, validity ICCs increased to 0.51 and 0.62 (p<0.05), and reliability improved to 0.40 for intensity and 0.33 for unpleasantness. SEM reduction indicated improved agreement with repeated measurements.

Conclusions: Adequate validity and reliability were observed for CPM applied to the affective dimension of pain. Reliability improved when three CPM repetitions were analyzed together, suggesting relevant temporal variability in endogenous pain inhibition. Assessing CPM effects on pain unpleasantness indicates that integrating the affective dimension may broaden the understanding of mechanisms involved in endogenous pain modulation.

References: 1. Price DD. Psychological and neural mechanisms of the affective dimension of pain. Science. 2000;288(5472):1769-1772.

2. Moont, R. et al. 'Pain inhibits pain' mechanisms: Is pain modulation simply due to distraction? Pain, v. 150, n. 1, p. 113-120, Jul 2010. ISSN 1872-6623.

3. Ibancos-Losada, M. D. R. et al. Exploring the Impact of Affinity and Unpleasantness on Conditioned Pain Modulation among Healthy Individuals. Biomedicines, v. 12, n. 6, May 25 2024. ISSN 2227-9059.

4. Nuwailati, R. Et al. Reliability of conditioned pain modulation in healthy individuals and chronic pain patients: a systematic review and meta-analysis. Scand J Pain, v. 22, n. 2, p. 262-278, Apr 26 2022. ISSN 1877-8879.

Presenting Author: Rhayane da Conceição Monteiro
Submitting Author: Rhayane da Conceição Monteiro

Senior Author: Yuri Martins Costa

IASP 2026 Global Year theme of Neuropathic Pain: No

• Rhayane da Conceição Monteiro - Department of Biosciences, University of Campinas, Piracicaba Dental School
• Isadora Alves Lorenzo - Department of Biosciences, University of Campinas, Piracicaba Dental School
• Allana Domingues Ferracioli - Department of Biosciences, University of Campinas, Piracicaba Dental School
• Fernando Exposto - Department of Dentistry and Oral Health, Section for Orofacial Pain and Jaw Function Aarhus University
• Leonardo Rigoldi Bonjardim - Department of Biological Sciences, Bauru School of Dentistry, University of Sao Paulo
• Mark Drangsholt - Department of Oral Medicine, University of Washington
• Peter Svensson - Faculty of Dentistry, National University of Singapore
• Yuri Martins Costa - Department of Biosciences, University of Campinas, Piracicaba Dental School