Classics in ECT: Depression Classification and ECT/Antidepressant Medication Response, British Journal of Psychiatry, 1983

 "Classics in ECT" brings you this study from The British Journal of Psychiatry, from 1983:

Classification of depression and response to antidepressive therapies.

Abou-Saleh MT, Coppen A.Br J Psychiatry. 1983 Dec;143:601-3. doi: 10.1192/bjp.143.6.601.PMID: 6229305

The abstract is copied below:

Two hundred inpatients suffering from primary depressive illness were studied. Seventy eight of the patients were treated by electroconvulsive therapy (ECT) and 122 patients received antidepressant medication. Response to ECT and antidepressant medication at 4 weeks showed a curvilinear relationship to Newcastle scores. Patients with Newcastle scores in the middle range (4-8) showed significantly higher percentage improvement than those with low (0-3) and high (9-12) scores. Ninety five patients with unipolar depression who received lithium therapy for one year were also studied. Response to lithium showed a linear relationship to Newcastle scores in these patients. It is suggested that these differences in response to antidepressant therapies reflect the heterogeneity of depressive illness.

The paper is here.

And from the text:

Here's an interesting study looking at a measure of  depression endogenicity (the Newcastle Scale) and severity (the HAMD, or "HRS" here) in relation to outcome. Interestingly, the Newcastle Score and HAMD are not tightly correlated in the ECT group (the patients with the highest Newcastle scores had slightly lower HRS than those with the middle range of Newcastle scores). Although the "percentage improvement" in the ECT group with Newcastle scores of 9-12 was less than those with scores of 4-8, it was still much higher (44%) than patients in the antidepressant medication group with scores of 9-12 (29%). The praise for lithium prophylaxis is not surprising, given the career focus of these investigators (please see also blog post of February 27, 2022, re these authors on lithium continuation after ECT.)

So, this is a bit of a mash-up of endogenicity and severity that sort of matches up to later data about  baseline depression severity as a predictor of ECT response...but it's complicated.

This very well-presented short classic deserves a full read, ~ 8 minutes.