The role of race and sex on experimental pain sensitivity in individuals with symptomatic knee osteoarthritis

Evidence suggests that experimental pain sensitivity varies across race and sex, with African Americans exhibiting increased perceptual responses to noxious stimuli when compared to non-Hispanic whites, and women demonstrating greater pain sensitivity than men. However, few studies have systematically assessed these differences in individuals with knee osteoarthritis (OA). Therefore, the aim of this study was to examine differences in experimental pain sensitivity across race (African Americans vs. non-Hispanic whites) in men and women with severe knee OA. Participants included 106 African Americans and 100 non-Hispanic whites (63 males, 143 females) who completed multiple experimental pain measures including contact heat, cold pressor, mechanical pressure, and punctate stimuli. Thresholds and tolerances to painful stimuli were measured, in addition to intensity and unpleasantness ratings. Results indicated that African Americans demonstrated lower pain thresholds and tolerances in response to multiple pain stimuli relative to non-Hispanic whites, and rated these stimuli as significantly more unpleasant and intense. Further, women exhibited lower heat and cold pressor pain tolerances, lower mechanical pain thresholds, and higher punctate pain intensity ratings than men. Results also indicated a significant Race X Sex interaction revealing that African American men rated noxious stimuli as more unpleasant and intense than non-Hispanic white men; however, these effects were only observed for cold pressor pain. Overall, these findings provide evidence of race and sex differences in experimental pain responses among individuals with symptomatic knee OA and suggest that race differences in cold pressor pain may be more marked for men than women. Further research is warranted to determine the specific mechanisms underlying these effects.