Differentiation between somatic and cognitive/affective components in commonly used measurements of depression in patients with chronic low-back pain. Let's not mix apples and oranges.

Patients with chronic low-back pain are frequently diagnosed as depressed. However, many of the neurovegetative signs of depression may also result from pain. The purpose of the present study was 1) to investigate the relationship between commonly used measurements of depression and pain perception; and 2) to examine the utility of differentiating between somatic signs and cognitive/affective symptoms of depression in patients with chronic low-back pain. The Beck Depression Inventory and the Hamilton Psychiatric Rating Scale for Depression were divided into cognitive/affective and somatic subscales. These measures, as well as the Minnesota Multiphasic Personality Inventory, were administered to 111 patients with chronic low-back pain. Analyses revealed significant correlations between depression scores and self-reported pain intensity. The cognitive/affective subscale of the Beck Depression Inventory resulted in the only nonsignificant correlation with pain intensity. These findings suggest that commonly used measurements of depression are confounded with pain symptomatology and that the cognitive/affective category of the Beck Depression Inventory may prove to be a more accurate measurement of depression in patients with chronic low-back pain.