Sex differences in pain drawing area for individuals with chronic musculoskeletal pain

STUDY DESIGN: Cross-sectional. OBJECTIVES: To (1) determine the association between pain severity and pain drawing area for men and women; (2) determine if sex differences exist in pain severity or pain drawing area; (3) determine the relative influence of pain severity, anatomical location of pain, personality, and psychological coping factors on pain drawing area for men and women. BACKGROUND: Pain drawings have been postulated to assist in clinical decision making regarding classification and treatment of musculoskeletal pain. Prior studies have been ambiguous on this topic, possibly because they have not considered if sex differences exist for pain drawing area. METHODS AND MEASURES: One hundred twenty-six subjects referred to a multidisciplinary chronic pain clinic with chronic musculoskeletal pain were included in this study. Subjects completed a pain drawing, the Multidimensional Pain Inventory (MPI), the Coping Strategies Questionnaire (CSQ), and the Minnesota Multiphasic Personality Inventory (MMPI-2). Pearson correlations investigated the associations of pain severity and pain drawing area, independent t tests investigated sex differences in pain severity and pain drawing area, and multiple regression investigated factors that influenced pain drawing area. RESULTS: Pain severity was positively correlated with pain drawing area for men (r = 0.38, P =.003) and women (r = 0.23, P = .052), accounting for approximately 14% and 5% of the total variance, respectively. There was no significant sex difference in pain severity ratings, but women reported a significantly larger area of symptoms on the pain drawings (effect size, 0.61; P = .002). The sex difference in pain drawing area was consistent across different anatomical locations of pain. In women, the final regression model accounted for 39% (P < .001) of the variance in pain drawing area, with anatomical location of pain (beta = .42, P < .001) and hypochondriasis (beta = .31, P = .005) as the only unique predictors in the final model. In men the regression model accounted for 27% (P = .003) of the variance in pain drawing area, with pain severity (beta = .32, P = .021) and a coping style of ignoring pain (beta = .32, P = .018) as the only unique predictors in the final model. CONCLUSIONS: Women had larger pain drawing area and this area was significantly associated with anatomical location of pain and hypochondriasis. Men had smaller pain drawing area and this area was associated with pain severity and a coping style of ignoring pain. These findings suggest that clinicians interpreting pain diagram area should consider the sex of the individual.