The presence of psychotic symptoms is an important predictor of responsiveness to electroconvulsive therapy (ECT). This study investigates whether a continuous severity measure, the Psychotic Depression Assessment Scale (PDAS), is a more accurate predictor.
Depression severity was assessed before and after the ECT course using the Montgomery-Asberg Depression Rating Scale (MADRS) in 31 patients with psychotic depression and 34 depressed patients without psychotic symptoms. Logistic regression models for MADRS response and remission were fitted, with either the PDAS total score or the dichotomous predictors “absence/presence of psychotic symptoms” as the independent variables. Age, episode duration, and treatment resistance were added as covariates.
Both the asserted presence of psychotic symptoms and a higher PDAS total score reflected MADRS response (areas under the curve, 0.83 and 0.85, respectively), with MADRS remission also being predicted by the presence of psychotic symptoms and higher PDAS scores (areas under the curves, 0.86 and 0.84, respectively). Age was a contributor to these prediction models, with response and remission rates being highest in the older patients. Psychotic Depression Assessment Scale scores decreased significantly during ECT: at end point, 81.5% of the patients showed significant response and 63.9% had achieved remission.
The PDAS indeed accurately predicts response to and remission after ECT in (psychotic) depression and most pronouncedly so in older patients but seems to have no clear advantage over simply verifying the presence of psychotic symptoms. This could be the consequence of a ceiling effect, as ECT was extremely effective in patients with psychotic depression.
ClinicalTrials.gov: Identifier: NCT02562846.