Chronic pain, depression, and the dexamethasone suppression test.

In most healthy individuals, dexamethasone suppresses adrenal cortisol production. However, in patients with major depression, non-suppression frequently occurs and thus may be a marker for depression. The purpose of the present study was to examine the relationship of dexamethasone suppression test (DST) non-suppression to clinical variables such as major depression, site and duration of pain, prior surgery, and medication use in 81 chronic pain patients beginning inpatient pain treatment (Inpt. Pain), and 33 medication-restricted outpatients with chronic back pain and depression (Outpt. Back). In the Inpt. Pain group, the specificity of DST non-suppression for depression was 82% and for sensitivity 24%. In the Outpt. Back group, its sensitivity was 18%. Within the diverse inpatient samples, there was 69% non-suppression in patients with headache pain only, compared to 15% in patients with other sites of pain (P less than 0.01), but there was no significant difference in depression rate between these two groups. In the Inpt. Pain group, non-suppressors also had significantly less prior surgery. In the Outpt. Back group, opioid use was significantly higher in non-suppressors (33%) than in suppressors (11%). In chronic pain populations, the DST appears not to be useful clinically for the detection of depression and may be significantly affected by clinical variables other than depression.