Start-stop recurrent-event data layout ($(\mathrm{start},\mathrm{stop}],\mathrm{event},\mathrm{id}$)

Represent each person's successive eligible episodes by separate left-open, right-closed intervals, retaining a common patient identifier and event-order information. A recurrence ends an interval and can be followed by another one; administrative censoring ends the final interval without an event. The row's entry time determines risk set membership. Multiple rows remain one patient history, with possible within-patient recurrent-event dependence.

A refractory period makes a patient ineligible for another event for a fixed time $r$ after a recurrence. Exclude this time from exposure and risk sets by delaying the next interval's entry to $t_k+r$. In a gap-time recurrent-event model measured from the previous event, the next interval enters at gap age $r$, not zero; the clock is not reset at the end of recovery.