Depression in chronic pain patients: relation to pain, activity, and sex differences.

Depression is commonly reported among chronic pain patients and receiving increased attention from clinicians and researchers. There is, however, little empirical evidence concerning variables that differentiate depressed from non-depressed chronic pain patients, and whether depression is related to factors such as gender, pain report, and activity. As part of a study to address these questions, 63 chronic pain patients completed daily diaries of activity, pain levels, and medication intake, and completed questionnaires and interviews assessing depression, medical history, and demographic variables. Male and female depressed and non-depressed chronic pain patients did not differ on demographic and medical history data, but sex differences were found in patterns of the relationships of depression, activity, and pain. For women, depression was closely related to pain report, whereas for men depression was more strongly related to impairment of activity. Pain report was related only minimally to activity for male and female patients. Implications of the results of behavioral research on depression in chronic pain patients are discussed. Researchers are urged to carefully consider sex differences in future research with chronic pain patients.