The epidemiology of pain in depression.

Over 75% of depressed patients in primary care complain of painful physical symptoms such as headache, stomach pain, neck and back pain as well as non-specific generalized pain. The presence of such symptoms predicts a greater severity and a less favourable outcome of depression with a poorer health-related quality of life. World Health Organization data obtained in primary care centres worldwide show that 22% of all primary care patients suffer from persistent debilitating pain and that these patients are four times more likely to have co-morbid anxiety or depressive disorder than pain-free primary care patients. Not unexpectedly, the risk of depression is greater when the pain is more diffuse, as indicated by the number of painful sites, and has a greater effect on the quality of life. Certain depressive symptoms, such as low energy and sleep disturbances, are commonly found in patients with co-morbid pain, whereas the opposite is true for symptoms such as guilt and loneliness. Increasingly, major depression is seen as being composed of psychological, somatic and painful physical symptoms. In order to achieve full sustained remission it is necessary to treat symptoms in all three of these areas. The area of painful physical symptoms is unfortunately still poorly understood and clearly merits greater attention.