Sex and pain-related psychological variables are associated with thermal pain sensitivity for patients with chronic low back pain

Biologic and psychological associations with evoked pain sensitivity have been extensively studied in healthy subjects but not among subjects with clinical pain syndromes. This study involved patients with chronic low back pain and investigated whether: 1) sex differences existed for thermal pain sensitivity; and 2) sex, fear-avoidance beliefs, and/or pain catastrophizing influenced thermal pain sensitivity. Thirty-three consecutive patients enrolled in a pain rehabilitation program completed self-report questionnaires and underwent quantitative sensory testing with an established protocol for thermal stimuli. Women had elevated pain sensitivity for measures of tolerance and temporal summation but not for first pulse response. In the multivariate models predicting thermal pain sensitivity, sex was associated with tolerance, and fear-avoidance beliefs were associated with first pulse response. Sex and pain catastrophizing were associated with temporal summation of thermal pain. Future studies involving clinical samples are necessary to replicate these findings and to explore the involvement of cortical structures. Perspective: This study suggests that sex, fear-avoidance beliefs, and pain catastrophizing were associated with thermal pain sensitivity for patients with chronic low back pain. These results corroborated sex differences in tolerance and temporal summation observed in the experimental pain literature for healthy subjects. These results also suggest the potential for these specific pain-related beliefs to be associated with a sensitized state because previous studies have demonstrated their association to clinical pain reports, and this study demonstrated associations with thermal pain sensitivity (C) 2007 by the American Pain Society.