Risk factors associated with fever after modified electroconvulsive therapy: A session-level study

To characterize fever within 24 h after modified electroconvulsive therapy (MECT) and to identify risk factors for post-MECT fever.

We retrospectively enrolled 451 patients with psychiatric disorders who underwent MECT at a single center between August 2021 and August 2022, comprising 3006 treatment sessions. Fever was defined as an axillary temperature ≥37.3 °C within 24 h after each session. Fever incidence and characteristics were summarized. Because multiple treatment sessions were nested within the same patient, a mixed-effects logistic regression model was used to evaluate associations of treatment session order, anesthetic regimen, demographic characteristics, and EEG seizure duration with post-MECT fever.

The patient-level incidence of fever was 20.18% (91/451), and the session-level incidence was 3.89% (117/3006). Fever episodes clustered within the first three sessions and were predominantly low-grade (65.8%). Mixed-effects logistic regression analysis showed higher fever risk during the first (OR 2.185, 95% CI 1.416-3.371, P < 0.001) and second (OR 3.113, 95% CI 2.080-4.659, P < 0.001) treatment sessions compared with sessions after the third MECT. Additionally, longer EEG seizure duration was independently associated with post-MECT fever (OR 1.011, 95% CI 1.001-1.020; P = 0.032).

Post-MECT fever was typically low-grade and more likely to occur during the early treatment sessions. Both treatment session order and EEG seizure duration were independently associated with post-MECT fever, highlighting the importance of balancing treatment adequacy with peri‑procedural safety, particularly during the early phase of MECT.