Within-session test-retest reliability of pressure pain threshold and mechanical temporal summation in healthy subjects

Catherine Mailloux,Louis-David Beaulieu,Timothy H Wideman,Hugo Massé-Alarie,Alison Rushton

doi:10.1371/journal.pone.0245278

Abstract

To determine the absolute and relative intra-rater within-session test-retest reliability of pressure pain threshold (PPT) and mechanical temporal summation of pain (TSP) at the low back and the forearm in healthy participants and to test the influence of the number and sequence of measurements on reliability metrics. In 24 participants, three PPT and TSP measures were assessed at four sites (2 at the low back, 2 at the forearm) in two blocks of measurements separated by 20 minutes. The standard error of measurement, the minimal detectable change (MDC) and the intraclass correlation coefficient (ICC) were investigated for five different sequences of measurements (e.g. measurement 1, 1-2, 1-2-3). The MDC for the group (MDCgr) for PPT ranged from 28.71 to 50.56 kPa across the sites tested, whereas MDCgr for TSP varied from 0.33 to 0.57 out of 10 (numeric scale). Almost all ICC showed an excellent relative reliability (between 0.80 and 0.97), except when only the first measurement was considered (moderate). Although minimal differences in absolute PPT reliability were present between the different sequences, in general, using only the first measurement increase measurement error. Three TSP measures reduced the measurement error. We established that two measurements of PPT and three of TSP reduced the measurement error and demonstrated an excellent relative reliability. Our results could be used in future pain research to confirm the presence of true hypo/hyperalgesia for paradigms such as conditioned pain modulation or exercise-induced hypoalgesia, indicated by a change exceeding the measurement variability.

Highlights

The experience of pain is highly variable and influenced by biological, psychological and social factors [1]
Our study focused on absolute reliability that will provide the minimal level to reach a real change in pain sensitivity, which is essential to interpret the presence/ absence of hyper/hypoalgesia using pain modulation paradigms such as Conditioned pain modulation (CPM) and exercise-induced hypoalgesia (EIH)
The minimal detectable change (MDC) obtained in our study provides specific threshold to determine if change in pressure pain threshold (PPT) or temporal summation of pain (TSP) in a within-session design exceeds the variability of these measures for a group (MDCgr)

Summary

Introduction

The experience of pain is highly variable and influenced by biological, psychological and social factors [1]. One essential feature of the experience of pain is the capacity of the nervous system to modulate pain through the interplay of multiple areas and mechanisms [2]. Psychophysical experimental paradigms have been developed in research as proxy of pain modulation. Conditioned pain modulation (CPM) and exercise-induced hypoalgesia (EIH), for instance, are used to approximate the efficacy of pain inhibition [3,4,5]. These paradigms have been increasingly used in research to determine if individuals with chronic pain have an altered pain inhibition response. Some studies reported an alteration of pain inhibition in individuals with chronic low back pain (CLBP) using CPM [6,7,8,9] and EIH [10,11]

Methods

Results

Discussion

Conclusion