Cold pressor pain responses in healthy Libyans: effect of sex/gender, anxiety, and body size

Abstract

Background: Studies have suggested that sex/gender, ethnicity, and anxiety toward pain affect pain sensitivity response. However, most studies have been conducted in a developed (Western) country, where the "ethnic" comparison group was in the minority.

Objectives: This study measured the responses of Libyan men and women to cold pressor pain, and also examined the effect of anxiety about pain and of body characteristics such as height, weight, and body mass index (BMI) on pain responses.

Methods: Students attending Garyounis University, Benghazi, Libya, took part in an experiment in 2007 that consisted of 2 cold pressor pain tests. During each test, participants plunged their nondominant hand into a slurry of ice. Time to pain threshold, time to pain tolerance (removal of the hand from the ice), and pain intensity and unpleasantness were measured using a 100-mm visual analog scale. Participants also completed a 20-item Pain Anxiety Symptoms Scale (PASS-20) questionnaire, with each item scored on a 6-point Likert scale anchored by descriptive phrases (0 = never, 5 = always).

Results: Fifty-eight self-declared students (29 men, 29 women; age range, 19-38 years) participated in the study. Pain threshold was significantly higher for men (mean difference, 8.2 sec; 95% CI, -1.7 to 18.0; P = 0.04), but there were no significant differences in pain tolerance, intensity, or unpleasantness. Women had significantly higher scores on the PASS-20 total score (P = 0.03), and on the PASS-20 dimensions of escape/avoidance (P = 0.04) and physiological anxiety (P = 0.006). Height, but not weight or BMI, was correlated with pain threshold in women (r = 0.52; P = 0.019) but not in men. Significant predictors of linearity of pain tolerance in women, but not men, were height (r = 0.49; P = 0.028) and the cognitive anxiety dimension score of the PASS-20 (r = -0.69; P = 0.004). Pain intensity rating was significantly higher in both women and men in the presence of an investigator of the opposite sex.

Conclusions: Libyan women had higher pain sensitivity response to cold pressor pain than did Libyan men, but both sexes had lower pain responses than their Western counterparts. Height and anxiety may have contributed to the differences between the sexes in this study.