Unreliability of the Cold Pressor Test Method in pain studies.

The Cold Pressor Test Method is one of the most widely used techniques in laboratory pain studies. Many research projects use it to evaluate analgesic therapies, including pharmacological methods. However, a review of these projects shows that both the way in which the test is applied and the results obtained from it differ widely. There is, therefore, an urgent need to establish optimal conditions under which reliable results can be obtained. We have analyzed the effect of test repetition on parameters normally used in this method. Our results show great variability, especially in some subjects, in the measurement of pain threshold, withdrawal threshold and subjective pain. Standardization of the technique, design of new evaluation methods and continual recording of the way in which subjects interact with laboratory conditions must be developed if we want to find valid results with the Cold Pressor Test method in pain studies.