2.3. Randomisation, Allocation Concealment and Blinding

A computer-generated, permuted, and stratified randomization sequence was produced before any patients were enrolled and before participants were allocated in permuted blocks of 2 to 6 to the MBI or TAU group (1:1); the randomization sequence (stratified by center) was prepared by a biostatistician with no clinical involvement in the trial (R.C.). The allocation was concealed in a password-protected computer file only accessible by the biostatistician. Individual allocations were held in sealed, opaque, and consecutively numbered emails which were sent to and opened sequentially by one of the clinical psychologists (ESB) on site. SAS PROC PLAN was used to generate the randomization schedules, specifically SAS statistical software version 9.4 (SAS Institute Inc., Cary, NC, USA). For feasibility reasons, the open-label design was used since the personnel and patients involved in the intervention as well as patients in the control group immediately became aware of treatment allocation after randomization (opening the specific envelop) and were thus not blinded during the remaining trial period.