Fig. 1

Traffic light system for moving from the pilot phase to the main phase. *Green: continue (i.e., no concerning issues that threaten the success of the trial); yellow: either adapt or continue with caution (i.e., remediable issues); red: stop or at least halt (i.e., intractable issues that cannot easily be remedied). Although it is foreseen to have only two to three sites in the pilot, using enrolment in the two best enrolling sites allows also for more sites in the pilot