Evidence for sex differences in the relationships of pain, mood, and disability

Disability demonstrates strong univariate associations with pain and negative mood. These relationships are more complex at the multivariate level and might be further complicated by sex differences. We investigated sex differences in the relationships of pain and negative mood to overall disability and to disability in specific functional domains. One hundred ninety-seven consecutive patients with low back, myofascial, neck, arthritis, and fibromyalgia pain were recruited from university pain clinics and completed measures of disability and negative mood. Overall disability and disability in voluntary activities were significantly associated with pain and negative mood (factor score) for both sexes. Significant sex differences emerged in the strength of the disability-mood relationship, with women evincing a stronger relationship. Disability in obligatory activities was also significantly related to pain and negative mood for both sexes; however, there were no sex differences in the strength of these relationships. Mediation analyses indicated that, in men, negative mood partially mediated the relationship between pain and both overall disability and disability in voluntary activities; mediation was not supported for disability in obligatory activities. In women, negative mood fully mediated the relationship between pain and all 3 types of disability. These data. suggest that disability is more directly related to pain in men. In women, the effect of pain on disability appears to operate through negative mood. Perspective: Results of this study demonstrate that sex differences exist in the relationships of pain, mood, and disability. Men and women might thus benefit from treatment interventions that differentially target these variables. (c) 2006 by the American Pain Society.