stop follow-up of a subset of enrolled patients at a specified time at or
after the current milestone. Data of affected patients are censored
(time-to-event endpoints) or set to missing (non-time-to-event endpoints
with readout after the stopping time), as if those patients were no longer
followed since then. This function can be used in adaptive designs; its
application includes, but is not limited to, treatment discontinuation,
early termination of follow-up for a sub-population, or enrichment design
where follow-up of a de-selected sub-population is stopped after an
interim analysis. It can also be called at a pre-specified milestone that
splits a trial into cohorts, e.g., a milestone marking the last patient
of the first cohort and the first patient of the second cohort. Such a
milestone is usually event driven, so its time is unknown until the trial
is simulated. Stopping follow-up of the earlier cohort at that milestone,
or after a pre-specified, fixed additional_followup beyond it,
makes statistics computed from the two cohorts independent, which
facilitates tests requiring independence, e.g., combination tests.
Only patients who are enrolled by the time this function is called and
satisfy the subset conditions in ... (if any) are affected.
Patients enrolled afterwards are followed as usual.
Note that this function should only be called within action functions of
milestones. It is users' responsibility to ensure that and
TrialSimulator has no way to track it. Calling it before any
milestone has been triggered is an error.
This is a user-friendly wrapper of the member function of trial, i.e.,
Trials$stop_followup(), which is used in vignettes. Users who are not
familiar with the concept of classes may consider using this wrapper
directly.
Arguments
- trial
a trial object returned by
trial().- ...
subset conditions compatible with
dplyr::filter. Follow-up is stopped for selected patients only. If no condition is provided, follow-up is stopped for all patients enrolled by the time this function is called.- additional_followup
numeric. Extra follow-up time granted to the selected patients after the current milestone. If 0 (default), follow-up stops at the milestone itself.