st: margins after stcox with time-dependent covariate

[petretta@unina.it]

Dear list members,

I use Stata/IC 12.1 for Windows (32 bit).
I ask if the margins command may be used after stcox with three fixed
covariates (gender, Y Z) and only one time-varying covariate. In
particular, I used stsplit to handle the time-varying covariate, a X
tratment in the course of follow-up and time_X is the wait time for the X
treatment: some subjects may also never have the X treatment. I use the
following code:

gen wait = time_X
replace wait =0 if wait==.
stsplit, at(failures)
generate postX = wait<_t & wait!=0
stjoin
stcox postX##gender Y Z

I ask if thereafter it is possible to use the margins command to estimates
margins of responses for specified values of covariates.

Thanks for your consideration

------------------
Mario Petretta
Department of Translational Medical Sciences
Naples University Federico II
Italy




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