Statistical analysis
SECONDARY, REMISSION, EVENT
The working hypotheses for the two coprimary endpoints were: the relapse rate would be higher in the infliximab withdrawal group as compared with the combination group and the immunosuppressant withdrawal group, but the mean restricted time spent in remission would not be inferior in the infliximab withdrawal group as compared with the combination group and the immunosuppressant withdrawal group. The sample size computation was based on hypotheses around the coprimary endpoints, thus a Bonferroni correction of size 2 was considered to control a global alpha risk of 0·05. We assumed a 2-year relapse rate of 10% in the combination group Continuous variables are summarised as median (IQRs) and categorical variables as counts (%).Analyses were performed on an intention-to-treat basis. All the patients who had undergone randomisation were analysed in the group they were allocated to. For the primary endpoints, the patients leaving the trial for other reasons than a relapse were censored at the time of drop out, as usually performed in time-to-event analyses. For the secondary endpoint concerning the proportion of patients in steroid-free sustained remission, patients leaving the trial early were considered as not being in sustained steroid-free remission.Comparisons between groups were performed only to compare the combination group versus the infliximab withdrawal group, and the infliximab withdrawal group versus the immunosuppressant withdrawal group. Failure-free survival and relapse-free survival were estimated by Kaplan–Meier estimators with 95% CIs. Survival curves were tested using log-rank tests. Factors associated with failure-free survival and relapse-free survival were assessed using Cox models. Hazard ratios (HR) with 95% CIs were computed. Multivariable analyses were performed including all factors significantly associated with failure-free survival and relapse-free survival. Mean restricted event times in remission were estimated and compared using the survRM2 R-package.All reported p values are two-sided; a p value of less than 0·05 was considered statistically significant. Statistical analyses were performed with SAS (version 9.4) and R (version 4.1.2) statistical software. This study is registered with 