Association of Anaesthesia-ECT time interval with ECT clinical outcomes: A retrospective cohort study

To examine the association of the anaesthesia to ECT stimulus TI (anaesthesia-ECT TI) with efficacy and cognitive outcomes after ECT treatment.

Retrospective cohort study of 690 patients who received ECT from July 2017 till December 2019. Generalized linear regression was utilized to analyse the association of mean anaesthesia-ECT TI (from session 2 to session 6 ECT treatment) with Clinical Global Impression-Severity scale (CGI-S) scores and Montreal Cognitive Assessment (MoCA) score after 6 ECT treatments, and with EEG quality during the treatments (post ictal suppression scores).

The averaged TI was 106.6±20.2 (mean±SD) seconds. There was significant improvement of overall CGI-S score after ECT treatment (3.3±1.0) vs pre-ECT treatment (5.0±0.8, p<0.001) while there was no significant change of MoCA score over the course of 6 ECT (p>0.05). The anaesthesia-ECT TI had no association with post-ECT CGI-S while longer anaesthesia-ECT TI was associated with poorer post-ECT MoCA scores [adjusted β, -0.056; 95% CI (-0.099, -0.013), p=0.011] and better EEG quality score [adjusted β (0.001), 95% CI (0, 0.002), p=0.011].

Longer TI between anaesthesia and ECT stimulus administration resulted in higher seizure quality, suggesting more effective stimulation. This was associated with more cognitive impairment but not higher efficacy. The assessment of outcomes after only 6 ECT limited the ability to fully explore associations between the TI and clinical outcomes. This was a retrospective analysis of clinical data from a real-world treatment setting. A controlled study would provide greater potential to fully explore the association between TI and clinical outcomes.