Quantitative sensory testing reliable for pain threshold, tolerance assessment

Quantitative sensory testing (QST) yields reliable measures of pain threshold and tolerance, reveals a new study. However, measurements for sensitivity to changes in temperature are less reliable and may be affected by time and other contextual factors.

A total of 171 healthy volunteers (99 women) participated in the study and were made to undergo QSTs across multiple visits. At each visit, participants underwent adaptive staircase pain calibration, consisting of 24 heat trials, and were then asked to rate pain intensity on a 10-point visual analogue scale (VAS).

For each participant, linear regression analysis was performed to identify pain threshold (temperature with VAS score 2) and pain tolerance (temperature with VAS score 8).

Using intraclass correlation (ICC) analysis, the researchers found moderate reliability of pain threshold measurements (ICC, 0.658). Including outliers (ICC, 0.626) or accounting for nonlinear correlations between pain and temperature (ICC, 0.559) did not meaningfully change the principal outcome.

Similarly, restricting analysis to the first two visits showed moderate reliability of pain threshold measurements (ICC, 0.619).

Pain tolerance was likewise moderately reliable overall (ICC, 0.67) and when including outliers (ICC, 0.624) or using only measurements from the first two visits (ICC, 0.681). Reliability decreased slightly when accounting for nonlinear associations (ICC, 0.431).

In contrast, the interaction between temperature and pain was unreliable, with an ICC of 0.171. Reliability estimates remained low regardless of analysis approach.

"Our work adds to a body of literature on QST reliability and suggests that different measures of pain sensitivity have different variability across time," the researchers said. "Future work on pain and its modulation should continue to understand the contextual factors that contribute to variability."