Thank you Dr. Hilbe. However, I think that this method
is only applicable to cohort studies and not to
case-control studies. Is that correct?
Thank you,
Ricardo
--- [email protected] wrote:
> 'ODDSRISK': module to convert Logistic Odds Ratios
> to Risk Ratios now on SSC
>
> I thought I had posted a notice about this module
> to the list yesterday, but
> it seems that it did
> not make it. I take the Digest, so do not see what
> is posted until the next
> day. I apologize if the earlier one is posted today,
> as well as this one.
>
> Zhang and Yu (1998, JAMA) proposed an algorithm to
> convert binary logistic
> regression odds ratios to estimated risk ratios. I
> have seen the method used
> in a number of medical research articles, and had
> written about the method in
> a book I am writing. I noticed a couple of Statalist
> communications during
> the past couple of weeks related to the relationship
> of odds ratio to risk
> ratio. I wrote about this relationship in my
> "Negative Binomial Regression", but
> not about this method and its rationale. Anyhow, I
> thought it might be helpful
> to those interested in using this method to release
> a Stata implementation
> now rather than with the forthcoming book several
> months from now. I wrote the
> program in such a manner that the logistic odds
> ratio, estimated risk ratio,
> and 95% confidence intervals of the estimated risk
> ratios are displayed for
> each predictor in the model. The incidence rate of
> the unexposed risk factor,
> or primary predictor of interest (binary (1/0)),
> which is required for
> calculation, is also displayed.
>
> The estimated risk ratios are particularly important
> when we wish to use
> terms such as "likely" in place of "odds of" when
> interpreting the odds ratio of
> a logistic model. This is primarily the case with
> the odds ratio is under
> 0.5 or over 2.5 and the incidence rate is greater
> than 10%. To say something
> like, "patients having an anterior infarct are 50%
> more likely to die within 48
> hours of hospital admission than are patients having
> just sustained an
> infarct at another primary site", is using risk
> language. Such language may be
> justified for many logistic models, but not all.
> Using the estimated risk
> values and CI's calculated by -oddsrisk- presumably
> enhance the justification for
> using risk language with logistic models when the
> conditions specified above
> obtain.
>
> Kit Baum has graciously posted the program, called
> -oddsrisk- and the
> associated help file to the SSC site. You can
> download it by typing
> . ssc install oddsrisk
> on the Stata command line.
>
> I have pasted the SSC site module description under
> my name below.
>
> Best, Joseph Hilbe
>
>
> DESCRIPTION/AUTHOR(S)
>
> oddsrisk converts logistic regression odds ratios
> to relative
> risk ratios. When the incidence of an outcome is
> common in the
> study population; i.e. greater than 10%, the
> logistic regression
> odds ratio no longer approximates the risk ratio.
> As the
> incidence rate becomes more frequent, the more the
> odds ratio
> overestimates the risk ratio when its value is
> greater than 1,
> and the more it underestimates the risk ratio when
> under one. J.
> Zhang and K. Yu proposed a method of adjusting the
> logistic
> regression odds ratio in a cohort study or clinical
> trial so that
> it approximates the risk ratio. This is
> particularly important
> when the odds ratio is greater than 2.5 or under
> 0.5. The method
> has also been shown to be applicable for
> retrospective and
> observational studies as well.
>
> Author: Joseph M. Hilbe
> Arizona State University
> [email protected] or [email protected]
>
>
>
>
> **************************************See AOL's top
> rated recipes
>
(http://food.aol.com/top-rated-recipes?NCID=aoltop00030000000004)
> *
> * For searches and help try:
> *
> http://www.stata.com/support/faqs/res/findit.html
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
>
Ricardo Ovaldia, MS
Statistician
Oklahoma City, OK
____________________________________________________________________________________
Looking for last minute shopping deals?
Find them fast with Yahoo! Search. http://tools.search.yahoo.com/newsearch/category.php?category=shopping
*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
