ON THE ABSENCE OF CORRELATION BETWEEN RESPONSES TO NOXIOUS HEAT, COLD, ELECTRICAL AND ISCHEMIC STIMULATION

Is a person's response to one noxious stimulus similar to his/her resp onses to other noxious stimuli? This long-investigated topic in pain r esearch has provided inconclusive results. In the present study, 2 sam ples were studied: one using 60 healthy volunteers and the other using 29 patients with coronary artery disease. Results showed near-zero co rrelations between measures of heat, cold, ischemic, and electrical la boratory pains, as well as between these laboratory pains and an idiop athic pain, the latency to exercise-induced angina in the patients. Po wer analyses showed that the sample sizes were sufficient to detect a correlation of 0.50 or greater at the 0.05 level 99% of the time in th e healthy volunteers, and between 80 and 85% of the time in the patien ts. Reliability analyses indicated retest correlations on the order of 0.60 for these measures, indicating that the lack of correlation betw een modalities was not due to unreliability within a measure. These st udies fail to demonstrate alternate-forms reliability among these test s, and also fail to support the notion that a person can be characteri zed as generally stoical or generally complaining to any painful stimu lus. In practice, this implies that a battery of tests should generall y be used to assess pain sensitivity and also that assessments of one pain modality are not generally useful for making inferences about ano ther.