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Re: R: st: Is there a similar command as roccomp for comparing two kaplan-meier curves?


From   "Roger B. Newson" <r.newson@imperial.ac.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: R: st: Is there a similar command as roccomp for comparing two kaplan-meier curves?
Date   Mon, 08 Oct 2012 14:04:55 +0100

One possibility here is to use the -somersd- package, downloadable from SSC, to compute a confidence interval and a P-value for the Gehan–Breslow–Wilcoxon Somers' D of survival time with respect to membership of Group 1 instead of Group 2. This practice is demonstrated in Subsection 5.2 of Newson (2006), which you can download free from the Stata Journal website at

http://www.stata-journal.com/article.html?article=snp15_6

I hope this helps. Let me know if you have any further queries.

Best wishes

Roger


References

Newson R. Confidence intervals for rank statistics: Somers' D and extensions. The Stata Journal 2006; 6(3): 309-334.

Roger B Newson BSc MSc DPhil
Lecturer in Medical Statistics
Respiratory Epidemiology and Public Health Group
National Heart and Lung Institute
Imperial College London
Royal Brompton Campus
Room 33, Emmanuel Kaye Building
1B Manresa Road
London SW3 6LR
UNITED KINGDOM
Tel: +44 (0)20 7352 8121 ext 3381
Fax: +44 (0)20 7351 8322
Email: r.newson@imperial.ac.uk
Web page: http://www.imperial.ac.uk/nhli/r.newson/
Departmental Web page:
http://www1.imperial.ac.uk/medicine/about/divisions/nhli/respiration/popgenetics/reph/

Opinions expressed are those of the author, not of the institution.

On 08/10/2012 09:43, Carlo Lazzaro wrote:
Dear Ton,
what follows might be of some help:
--------------------------------------------------------------
use http://www.stata-press.com/data/r12/stan3
g A=2 if surgery==1 & transplant==1
replace A=1 if surgery==0 & transplant==1
replace A=0 if surgery==0 & transplant==0
sts graph, by(A)
sts test A, logrank
--------------------------------------------------------------

Take a look at - help sts test - for further details.

Kindest Regards,
Carlo



Dott. Carlo Lazzaro
Studio di Economia Sanitaria
Via Stefanardo da Vimercate, 19
20128 Milano
Tel/fax: 02/26000516
Portatile: 335/6786741
e-mail: carlo.lazzaro@tiscalinet.it
                carlo.lazzaro@tin.it

-----Messaggio originale-----
Da: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] Per conto di
A.J.M.de_Craen@lumc.nl
Inviato: lunedì 8 ottobre 2012 10:00
A: statalist@hsphsun2.harvard.edu
Oggetto: RE: st: Is there a similar command as roccomp for comparing two
kaplan-meier curves?

Thank you Steve, I was indeed not completely clear. Let me retry.
For 600 individuals I have calculated two measures of kidney function based
on different blood parameters. First, I select those with a poor kidney
function based on one variable, and run a survival analysis. Then I select
those with a poor kidney function on the other variable, and run a survival
analysis again. Obviously, there are many individuals in both analyses, but
some only have a poor kidney function on one variable, and others only on
the other. When I look at the two Kaplan-Meier curves in one graph, I see a
clear difference between the two lines. How do I test whether they are
statistically significant from each other?
Regards,
Ton



-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Steve Samuels
Sent: maandag 8 oktober 2012 4:02
To: statalist@hsphsun2.harvard.edu
Subject: Re: st: Is there a similar command as roccomp for comparing two
kaplan-meier curves?



Your question is not clear. There cannot be two KM curves that both are
based on the same individuals, as the KM curve is unique, given the sample.
As asked in the FAQ Section 3.3, please show us the Stata commands that
produce the KM curves that you wish to compare. If you can, illustrate the
problem in one the data sets referenced in the
-help- for the command.


Steve


On Oct 7, 2012, at 3:32 PM, <A.J.M.de_Craen@lumc.nl>
<A.J.M.de_Craen@lumc.nl> wrote:

Is there a similar command as roccomp for comparing two kaplan-meier curves?
I want to compare the predictive value of two different variables in the
same dataset. Note that the all individuals are in both K-M curves.
Thanks,
Ton de Craen
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