Validation Of Interindividual Differences in Pain Sensitivity Through Noxious Stimulus Discrimination

The experience of pain varies greatly among individuals. Quantifying these differences remains challenging due to the difficulty of separating individual differences in scale usage/reporting from true differences in perception. Previous results from our lab suggest that assessing pain discrimination may provide one solution to this problem since interindividual differences in pain are associated with differences in the ability to discriminate temperature changes (Hoeppli, 2022). In this study, we prospectively investigated the relationship between pain sensitivity and noxious heat discrimination. Forty-eight healthy volunteers (54% female) first rated perceived pain intensity and unpleasantness of 32 5-second heat stimuli using VAS. A latent profile mixture model yielded three distinct pain sensitivity classes: low, moderate, high. Participants then completed a dynamic discrimination task. In this task they reported changes in heat stimuli using a Likert-type scale. Each stimulus started at a T1 temperature (43°C, 45°C, or 47°C) that changed by one step (0.0˚C, +0.3°C, +0.6°C, or +0.9°C). Preliminary results from a Generalized Estimating Equation model indicated that pain sensitivity, T1 temperature, and step had a significant interactive effect on participants' reports of temperature changes. Post-hoc analyses identified significant differences in detected temperature changes among sensitivity classes. Taken together, these findings confirm that VAS ratings of pain are sufficient to capture interindividual differences in perceived pain magnitude. This is an important step to better understand the mechanisms supporting interindividual differences in pain. Future studies are needed to define their role in chronic pain and its treatment. Funded by National Institutes of Health (R01 NS085391).