| Background Modified electroconvulsive therapy (MECT) is a physical therapy widely used in the front line of psychiatric clinics, and the optimal first stimulation dose of MECT is usually estimated clinically based on the factors influencing the patient's initial seizure threshold (IST). However, previous studies on the influencing factors of IST are often characterized by sample size limitations and a single research dimension. Objective Exploring the factors influencing IST in patients with mental disorders to inform the selection of quantitative IST for MECT in patients with mental disorders. Methods A retrospective study was used to include 1,446 patients with mental disorders who were hospitalized and underwent MECT at Daizhuang Hospital, Shandong Province, from January 1, 2021, to August 1, 2023, and who met the ICD-10 diagnostic criteria, and to collect their general and clinical data, including IST, diagnostic category, gender, ethnicity, age, body mass, body mass index (BMI) ), duration of illness, family history of psychiatric disorders, whether or not to debut, whether they were taking antiepileptic drugs on the day before treatment, whether they were taking benzodiazepines on the day before treatment, and whether they had a history of MECT treatment. Pearson correlation analysis was used to examine the correlation between patients' IST and age, height, body mass, BMI, and disease duration; multiple linear stepwise regression analysis was used to examine the factors affecting patients' IST. Results ① There were statistically significant differences in IST among patients with different gender, whether or not to debut, whether taking antiepileptic drugs the day before treatment, and whether taking benzodiazepines the day before treatment (t=2.256, -3.059, -2.136, -3.006, P<0.05 or 0.01). There were statistically significant differences in IST between patients of different ages and different diagnostic categories during MECT (F=913.120, 6.212, P<0.01). ② In young people, there was a significant difference in IST between patients with different diagnostic categories during MECT (F=2.986, P<0.05). ③ Correlation analysis showed that IST was positively correlated with age, body mass, BMI and course of disease (r=0.886, 0.055, 0.184, 0.456, P<0.05 or 0.01), and negatively correlated with height (r=-0.183, P<0.01). ④ Multiple linear stepwise regression analysis showed that age, sex, and body mass were predictors of IST (β=0.888, -0.049, -0.035, P<0.01). Conclusions Factors influencing IST in patients with psychiatric disorders included gender, whether it was the first episode, use of antiepileptic drugs or benzodiazepines on the day before treatment, age, diagnostic category, body mass, BMI, and duration of illness. In young patients, different diagnostic categories had a significant effect on IST. In addition, age, gender, and body mass were predictors of IST. |