Statistical Methods
NSI, Suicide Ideation
Continuous variables and nominal variables were analyzed using 1-way ANOVA and Fisher’s chi square tests, respectively, to assess differences between the 2 infusion groups (0.5 mg/kg ketamine or 0.045 mg/kg midazolam) with respect to demographic and clinical data. The generalized estimating equation (GEE) models with the autoregressive method for correlations of repeated measures for the same individual over time and with the adjustment of age, sex, and baseline clinical symptoms were used to assess the trajectories of total MADRS, MADRS item 10, total CSSRS-ISS, and PANSI-Positive Suicide Ideation (PSI) and Negative Suicide Ideation (NSI) scores during the study period with the infusion group (0.5 mg/kg ketamine vs 0.045 mg/kg midazolam) as a between-patient factor and time (baseline, infusion, and follow-up) as a within-patient factor as well as all possible interactions. In addition, we examined the roles of 3 clinical factors, including treatment refractoriness (low and moderate vs high), duration of current episode (<24 vs ≥24 months), and failure numbers of antidepressants (≤4 vs >4), on the trajectories of the above clinical symptoms. Furthermore, owing to the evidence that the duration of the antisuicidal effect of ketamine infusion may not be longer than 1 week (