Test-Retest Reliability of Thermal Temporal Summation Using an Individualized Protocol

Temporal summation (TS) refers to the increased perception of pain with repetitive noxious stimuli. It is a behavioral correlate of wind-up, the spinal facilitation of recurring C fiber stimulation. In order to utilize TS in clinical pain research, it is important to characterize TS in a wide range of individuals and to establish its test-retest reliability. Building on a fixed-parameter protocol, we developed an individually adjusted protocol to broadly capture thermally-generated TS. We then examined the test-retest reliability of TS within-day (inter-trial intervals ranging from 2 minutes to 30 minutes) and between-days (inter-session interval of 7 days). We generated TS-like effects in 19 of the 21 participants. Strong correlations were observed across all trials over both days [ICC (A, 10) = 0.97, 95% CL = 0.94 to 0.99] and across the initial trials between days [ICC (A, 1) = 0.83, 95% CL = 0.58 to 0.93]. Repeated measures mixed effects modeling demonstrated no significant within day variation, and only a small (5 out of 100 point) between-day variation. Finally, a Bland-Altman analysis suggested that TS is reliable across the range of observed scores. Without intervention, thermally-generated TS is generally stable within-day and between days. Perspective: Our study introduces a new strategy to generate thermal TS in a high proportion of individuals. This study confirms the test-retest reliability of thermal TS, supporting its use as a consistent behavioral correlate of central nociceptive facilitation