Clinical Science (34)

Abstract

D. Sheffield, P.L. Biles, H. Orom, W. Maixner, D.S. Sheps: Race and sex differences in cutaneous pain perception. (University of North Carolina at Chapel Hill, Chapel Hill, NC) Psychosomatic Medicine 2000;62:517–523.The purpose of this study was to determine race and sex differences in cutaneous pain perception. Pain perception was measured using a suprathreshold evaluation of pain intensity and pain unpleasantness to a series of thermal stimuli in 27 whites (14 men and 13 women) and 24 African‐Americans (12 men and 12 women). Blood pressure, depressive symptoms, anxiety state levels, and negative mood were assessed before pain testing to examine whether they might account for any sex or race differences in pain perception that emerged. African‐Americans rated the stimuli as more unpleasant and showed a tendency to rate it as more intense than whites. Women showed a tendency to rate the stimuli as more unpleasant and more intense than men. In addition, systolic blood pressure was inversely related to pain intensity. After statistically adjusting for systolic blood pressure, sex differences in pain unpleasantness were reduced and sex differences in pain intensity were abolished; race differences were unaltered. These differences in pain perception may be associated with different pain mechanisms: in the case of sex, differences in opioid activity and baroreceptor‐regulated pain systems; in the case of race, unmeasured psychological characteristics are suggested by the larger differences in ratings of pain unpleasantness than pain intensity. Comment by Mauricio Orbegozo, MD.This is a study where the authors look to elucidate whether there was a difference in cutaneous pain perception determined by race or sex. In general, it is a very well‐designed study where 2 different groups were evaluated, 1 of 27 whites and 1 of 24 African‐Americans with close to half and half distribution of men and women. Pain perception was measured using pain intensity and pain unpleasantness to a series of thermal stimuli. Five different temperatures were used on each subject ranging from 45°C to 49°C. The pain scoring was carried upon a scale from 0 to 150 represented as a line where the evaluated subject had to mark the line at a certain height according to their pain perception. The conclusions reached in the study show that, in general, whites rated the thermal stimuli less painful than African‐Americans. The results show a tendency for men to rate the thermal stimuli as less painful than women did. One of the interesting findings in this study was that the pain differences between men and women were diminished after statically adjusting for systolic blood pressure level. However, the pain intensity and the pain differences after adjusting for systolic blood pressure were unaltered for race differences.In addition, it was also found that pain perception and pain rating was inversely proportional to systolic blood pressure. The hypoalgesia caused by increased systolic blood pressure is a poorly understood mechanism. Several studies have shown that in hypertensive rats there is increased opioid activity in brain tissue. These studies have suggested that at the increase of the pain threshold in subjects who have elevated blood pressure may be related to opioid activity. It is important to mention that in order to establish a definite correlation between systolic blood pressure elevation and the decreased pain perception more studies have to be done.Another important point in this study is the influence of psychological factors on pain perception. In general, it was seen that individuals that were psychologically rated as depressive had a higher rating of the pain compared to individuals that tested as high for anxiety.