R help - Oct 2011 - cph/nomogram Design/RMS package hazard ratio: interquartile vs per unit

Hello,

I am constructing a nomogram using cph and nomogram commands in Dr.
Harrell's Design/RMS package. The HR that I obtain for dichotomous and
categorical variables are identical to those that I obtain using STATA
stcox. However, the inter-quartile HR I obtain for continuous variables is
obviously different, since STATA gives me HR for each unit (year,
centimeter, etc) like coxph would give. My question is if this will effect
the output of the nomogram. I'm assuming that nomogram is constructed using
hazard between each unit rather than quartiles - is this true? 

Also, I've found that I do not need to create indicator variables for my
categorical variables when I use cph. Is this also correct? 

I appreciate your feedback. Thank you.

~Renee

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On Oct 20, 2011, at 8:22 PM, renee wrote:
> Hello,
>
> I am constructing a nomogram using cph and nomogram commands in Dr.
> Harrell's Design/RMS package. The HR that I obtain for dichotomous and
> categorical variables are identical to those that I obtain using STATA
> stcox.
When posting to r-help it is advised to produce the code used. One  
might guess that you were talking about output from summary(fit) but  
that would be a guess.
> However, the inter-quartile HR I obtain for continuous variables is
> obviously different, since STATA gives me HR for each unit (year,
> centimeter, etc) like coxph would give.
If you want HR's for single unit difference on the scale of the  
measured units then this should produce those:

exp(coef(fit))
> My question is if this will effect
> the output of the nomogram. I'm assuming that nomogram is  
> constructed using
> hazard between each unit rather than quartiles - is this true?
Yes.
>
> Also, I've found that I do not need to create indicator variables  
> for my
> categorical variables when I use cph. Is this also correct?
If they are factor classed variables, then that is
correct.
>
> I appreciate your feedback. Thank you.
>
> ~Renee
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/cph-nomogram-Design-RMS-package-hazard-ratio-interquartile-vs-per-unit-tp3923896p3923896.html
> (At least until Nabble deletes it in a year or two.)
-- 

David Winsemius, MD
West Hartford, CT