st: Time-dependent variables and the simon & makuch method

[Florian Posch <florian.posch@meduniwien.ac.at>]

Dear Statalisters,

your help would be very much appreciated on the following:

I'm working on a dataset where I am modeling the impact of a 
time-dependent variable (the onset of thrombosis during follow-up) on 
survival. This analysis works fine with stsplit, and is pretty much the 
same as done in the Stanford Heart Transplant data example:

The Stata Journal (2004) 4 , Number 2, pp. 221–222
Stata tip 8: Splitting time-span records with categorical time-varying 
covariates

Again, my analysis works well for the Cox model, Kaplan-Meier survival 
curves, and the logrank-test (as illustrated in the Staa journal paper 
above). However, some recent reviews postulate that time-dependent 
covariates can validly be used in the Cox model but that is is 
INAPPROPRIATE to use them in Kaplan-Meier survival curves and the 
logrank test. These reviews suggest that the appropriate substitute 
methods in this setting are the Simon & Makuch plot (substitute for 
Kaplan-Meier curves), and the Mantel-Byar test (substitute for the 
logrank test).

Searching the web I found some posts in forums and a couple of papers on 
Pubmed which say that Stata has implemented these methods, however, I 
could not find such a package on the SSC or anywhere else in Stata. A 
prior post regarding this issue on statalist remained unanswered:

http://www.stata.com/statalist/archive/2010-05/msg00079.html

Do you know where I can find these analysis methods for Stata?

Thank you very much in advance for your input!

Flo

Florian Posch, MSc
MD PhD Student
Medical University of Vienna
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