Robustness of the cold pressor test: Study across geographic locations on pain perception and tolerance.

The cold pressor test, in which subjects immerse part of an extremity in cold water for a specified amount of time, evokes both pain and unpleasantness. As it is low cost and readily available, it is widely used in pain research. However, data on the impact of race, area of exposure, and the effects of instructions are lacking. Cold pressure test data were recorded in a mixed Asian and European healthy population. Trial 1 was a randomised crossover trial varying the extent of hand submersion (two fingers, four fingers, and whole hand) (n = 54). Trial 2 was a randomised cross-sectional design, investigating instructed and non-instructed pain expectations, n = 40. European subjects tolerated the cold pressor test longer than Asian subjects (116 ± 14 versus 93 ± 36 s, p < 0.001), and fewer subjects withdrew their hand in less than two minutes (9% vs 43%, p = 0.007). Stimulation area influenced pain tolerance, with more subjects able to maintain two-finger immersion in cold water for 2 min compared to whole-hand immersion (p < 0.001). The instruction or no instruction did not affect the numeric rating scale when comparing instruction levels (p = 0.88). Additionally, pain tolerance was not affected either (p = 1). The cold pressor test is a robust tool across genders, race, and instruction levels. Significant differences were found in pain perception and tolerance across different locations and stimulation intensities. However, instructions in expected pain did not affect the outcomes, reflecting the robustness of the test.