Reliability of Temporal Summation of Pain in Healthy and Clinical Populations: A Systematic Review and Meta-Analysis

Temporal summation of pain (TSP) is a dynamic quantitative sensory test reflecting pain facilitation. Variability in TSP paradigms challenges cross-study comparisons and raises concerns about reliability. This systematic review and meta-analysis evaluated the reliability of TSP in healthy and clinical populations.

Four databases were searched for peer-reviewed studies up to July 2024. Risk of bias and study quality were assessed. A random-effects meta-analysis was conducted to estimate intraclass correlation coefficients (ICC).

Twenty-two studies met inclusion criteria, with data from healthy (n = 12) and clinical (n = 7) populations. TSP was assessed using absolute change (difference between first and last stimuli) and relative change (ratio of first to last). ICCs ranged from -0.31 to 0.97. In healthy participants, between-session reliability was poor (ICC = 0.49, 95% CI: 0.40-0.58, I² = 81.4%, 35 estimates, 1208 subjects), while within-session reliability was moderate (ICC = 0.69, 95% CI: 0.61-0.77, I² = 91.7%, 28 estimates, 728 subjects). Highest reliability was seen for within-session testing using absolute change (ICC = 0.81, 95% CI: 0.74-0.88, I² = 0%). In clinical populations, between-session reliability was moderate (ICC = 0.57, 95% CI: 0.44-0.69, I² = 80.8%, 13 estimates, 470 subjects); within-session reliability was also moderate (ICC = 0.61, 95% CI: 0.46-0.76, I² = 89.6%, 10 estimates, 381 subjects). Study quality ranged from very good to excellent, with bias rated from doubtful to adequate.

TSP demonstrates moderate reliability, influenced by stimulus parameters and population. Small-area mechanical stimuli (e.g., pinprick), tested at 1 Hz using absolute change scores, yield the most reliable results. Further research is needed in clinical populations to better understand TSP mechanisms.

This review suggests that TSP is a reliable measure, with small contact area mechanical stimulus with absolute change calculation method, applied at a rate of 1 Hz, was found to be most reliable. Results highlights the need for standardisation, and consistency in data reporting. While most TSP paradigms were found to have moderate to good reliability, consideration should also be given when translating experimental TSP testing to clinical routine assessment.

PROSPERO number: CRD42024566623.