Fear of Severe Pain Mediates Sex Differences in Pain Sensitivity Responses to Thermal Stimuli

The purpose of this paper was to examine the relationship of sex and pain-related fear in pain intensity reports to thermal stimuli and whether sex differences in reported pain intensity were mediated by pain-related fear. 177 participants, 124 female (23.5 ± 4.5 years old), filled out a demographic and fear of pain questionnaire (FPQ-III). Experimental pain testing was performed using thermal stimuli applied to the lower extremity. Participants rated the intensity of pain using the numerical pain rating scale (NPRS). Independent t-tests, Sobel's test, and linear regression models were performed to examine the relationships between sex, fear of pain, and pain sensitivity. We found significant sex differences for thermal pain threshold temperatures (t = 2.04,  P = 0.04) and suprathreshold pain ratings for 49°C (t = -2.12,  P = 0.04) and 51°C (t = -2.36,  P = 0.02). FPQ-severe score mediated the effect of suprathreshold pain ratings of 49° (t = 2.00,  P = 0.05), 51° (t = 2.07,  P = 0.04), and pain threshold temperatures (t = -2.12,  P = 0.03). There are differences in the pain sensitivity between sexes, but this difference may be mediated by baseline psychosocial factors such as fear of pain.