A case-matching study of the analgesic properties of electroconvulsive therapy

Chronic pain improves with electroconvulsive therapy (ECT), yet few case reports account for treatment of comorbid major depression, a significant confounder of the analgesia of ECT. This study reports on the analgesia of ECT, controlling for treatment of depression.

This is a case-matching study comparing outcomes of inpatients with chronic pain and major depression in a multidisciplinary pain treatment unit treated with ECT and medications (cases) with those of inpatients treated with medications only (controls). Both groups received the same behavioral and pharmacological treatments for depression and chronic pain. Outcome measures included 0-10 pain rating scales and the Montgomery-Asberg Depression Inventory. Patients were matched on sex, age within 5 years, admission date within 6 months, psychiatric diagnoses, and, as much as possible, on race and pain syndrome diagnosis. Percentage changes in depression scores and pain scores were calculated from the beginning to the end of admission.

There were nonsignificant differences in demographics, except in the proportion married. Twenty-five of 28 ECT patients were matched. Depression improvements were similar between cases and controls (55.9% vs 40.5%). Despite higher initial pain (8.1 vs 6.9 on a 10-point scale), the ECT group had less final pain (3.4 vs 5.5). The ECT group had a 59.8% drop in pain versus a 15.8% drop in the control group, P > 0.01.

ECT has analgesic properties independent of its improvement of depression in patients with chronic pain and major depression. Improvements in depression were similar, while there was a significantly greater improvement in pain with ECT. The lower post-ECT treatment pain scores suggest a specific analgesic effect of ECT.