phguardiol@aol.com wrote:
Dear S users,
is there a way, I mean a package, to perform a competing risk model
which can handle time dependent covariates ?
my main covariate (additional treatment to patients) appears not to
follow the proportional hazards assumption, its effect being observed
after one year of treatment but not before (this is expected / makes
sense on a clinical point of view). SO I was planning to use a time
dependent Cox model with 2 time intervals for patients < > 1 year etc...
Philippe,
As your main covariate is an internal time-dependent covariate, it will
be impossible to interpret its effect without having in the model (to
condition on) the variables that indicate the reason for the treatment.
These variables need to be measured before the auxiliary treatment.
This is to get around "treatment by indication" bias.
I don't know the answer to your question, though. I hope there is some
S-Plus or R software for time-dependent covariates with competing risks
as we may have need for that also.
Frank
However, a large number of patients dies from treatment related
complications of unrelated to the disease and the treatment (elderly
patients) so to analyze the effect of my covariate of interest on
disease free survival and relapse incidence, I d like to use a competing
risk model such as the Gray CMPRSK.
My problem is that I cannot have multiple "lines" for the same patient
with this package (for time dep covariates 2 or 3 lines with same Id /UPN).
How can I manage this !!!???
Any help will be greatly appreciated
Thanks
Yours sincerely
Philippe Guardiola
--
Frank E Harrell Jr Professor and Chair School of Medicine
Department of Biostatistics Vanderbilt University
|