Test-retest reliability of pressure pain threshold and heat pain threshold as test stimuli for evaluation of conditioned pain modulation - 23/07/21

Doi : 10.1016/j.neucli.2021.06.005

Milena Kovacevic ^a,^⁎ , Ljiljana Klicov ^b, Dragana Vuklis ^a, Randy Neblett ^c, Aleksandar Knezevic ^a,^b
^a University of Novi Sad, Faculty of Medicine, Novi Sad, Serbia
^b Medical Rehabilitation Clinic, Clinical Centre of Vojvodina, Novi Sad, Serbia
^c PRIDE Research Foundation, Dallas, TX, United States of America

^⁎Corresponding author.

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Abstract

Objectives

There is growing interest in conditioned pain modulation (CPM) protocols for evaluating the function of the descending pain-modulatory system in clinical settings. The aim of this study was to evaluate test-retest reliability of a CPM protocol with contact heat as a conditioning stimulus (CS) and two test stimuli (pressure pain threshold (PPT) and heat pain threshold (HPT)), all applied within one session. In addition, gender and age differences were evaluated.

Methods

The study included 87 healthy subjects (average age 37.95 ± 12.02 years, 57.5% females). The magnitude of the results of the CPM test was calculated as the difference between subject-reported pain thresholds before and after application of the CS. To assess the reliability of the protocol, a subgroup of 66 subjects underwent re-test after 14±1 days. In order to investigate the influence of age on the CPM magnitude, subjects were divided into subgroups (20–29, 30–39, 40–49, 50–59 years).

Results

The pain thresholds for both test stimuli (TS) were significantly higher following the application of the CS (p < 0.001). Values of the interclass correlation coefficient (ICC) for the CPM with PPT as the TS indicated good reliability (ICC=0.631, 95% CI:0.365–0.782), while those for the HPT indicated poor reliability (ICC=0.328, 95% CI:-0.067–0.582). Significant differences in CPM between genders were found for both TS. Significant CPM differences were not detected among the four age subgroups for either TS.