Spss statistics software version 27.0 for windows

All patients included in the RCT were analysed according to the originally allocated treatment group. The RCT was powered to test the effect of IHT on the number of inpatient days (primary outcome) [13 (link)] and not specifically to be able to test for effect modification.
Patients’ characteristics were analysed using a standard approach including descriptive statistics and appropriate statistical tests. Multiple regression analysis was used to examine which patients’ characteristics moderate the effect of the intervention on symptom severity. Assumptions for regression analyses (linearity, homoscedasticity, normality of the residuals, absence of multicollinearity) were checked and met. For each potential moderator variable a separate regression model was fitted. Each model included baseline BPRS symptom severity, a treatment condition dummy variable (0 = CAU; 1 = IHT), the baseline value of the evaluated prescriptive variable and the prescriptive variable-by-treatment condition interaction term. Pairwise deletion was used for missing data.
All statistical analyses were performed using SPSS Statistics software version 27.0 for Windows (IBM Corp. Released 2020) and all two-sided statistical tests were performed with a significance level of α < 0.05.