Background: Although the dosage of electroconvulsive therapy (ECT) stimulus has a major impact on the efficacy and safety of this treatment, the method used to determine an optimal dosage remains a matter of debate.
Objective: We investigated factors influencing the seizure threshold (ST) in a large-sample study and compared age-based and titration dosing methods in terms of charge.
Methods: A retrospective study examined data from 503 patients across France and Canada. The patients underwent right unilateral (RUL) or bitemporal (BT) ECT during a titration session before undergoing ECT. Seizure threshold and charge differences between age-based and titration-predicted methods were derived for each RUL and BT patient and compared according to sex, age, and anesthetic agents.
Results: Based on our results, ST is a function of electrode placement, sex, age, and anesthetic agents. Titration and age-based methods led to completely different patterns of charges for the same electrode placement, especially in elderly and in women in the RUL group. Regression models showed that differences between the age-based and titration methods varied with respect to age, sex, and anesthetic agent. Specifically, significant effects of sex and age were observed for RUL ECT and of sex and anesthetics for BT ECT.
Conclusions: This study revealed that several factors significantly influence the prediction of ECT dose, depending on individuals and treatment modalities. Caution should be exercised when using nonindividualized methods to calculate ST.