[R] conditional gap time frailty cox model for recurrent events

[Elisabetta Petracci]

Dear users,

I am fitting a conditional gap time frailty cox model weighting
observations by means of inverse probability time dependent weigths.
Attached find the self-explaining dataset.

I have used the following sintax:

coxph(Surv(gaptstart,gaptstop,status)~treat+strata(nrecord01)+frailty(id,distribution="gamma",method="em"),
data=dataNOTDrr,weights=dataNOTDrr$weight)


And I get the following warning:

Warning message:
In coxpenal.fit(X, Y, strats, offset, init = init, control, weights =
weights,  :
  Inner loop failed to coverge for iterations 3 4


I have tried to:
- leave out the weights but I get the error anyway
- to randomly select a subset of patients and I don't get the error. This
seems to suggest that the problem is with some observations.

Any suggestion?

Many thanks,

Elisabetta