Electroconvulsive therapy in depressive illness that has not responded to drug treatment

Antidepressant medication resistance is the commonest indication for electroconvulsive therapy (ECT) in Scotland. Evidence from the USA suggests that clinical response is reduced for medication resistant patients. The aim of the present study was to establish if the American results were generalisable to routine clinical practice in Edinburgh.

Fifty eligible depressed patients consecutively referred for a new course of bilateral ECT at the Royal Edinburgh Hospital were prospectively assessed as part of the National Audit of ECT in Scotland. The patients were categorised into those who had received adequate drug treatment pre-ECT (and could therefore be classed as medication resistant) and those who had not, using five operational definitions. The clinical response of the ECT was then compared between groups, using the Montgomery-Asberg Rating Scale for Depression (MADRS) and Clinical Global Impression Scale (CGI).

Patients defined as medication resistant had an identical response to patients who were not defined as medication resistant (in both groups 60% met the predetermined criterion for clinical response), and this was consistent across the five operational definitions.

The hypothesis that medication resistance is associated with a reduced probability of clinical response to ECT was not supported.

Some patients who were inadequately drug treated might have proven eventually to be medication resistant, which would have obscured a potential difference in clinical response. It is not known how generalisable the results are to clinical practice in the rest of the UK.