Statalist


[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

Re: st: Trend test in meta analysis


From   "Tom Trikalinos" <[email protected]>
To   [email protected]
Subject   Re: st: Trend test in meta analysis
Date   Fri, 21 Dec 2007 16:59:46 -0500

Hi vijay

I'm not clear what form your data have.

Let me say right off the bat that such a question (dose-response)
could be evaluated on a qualitative basis (with a plot) without giving
a p-value. This should not be discarded as an option, given the strong
assumptions that are inherent in the data-abstraction process during
meta-analysis.

That being said see if the paper by Jesse Berlin et al.
"Meta-analysis of epidemiologic dose-response data." Epidemiology.
1993 May;4(3):218-28. PMID: 8512986 helps.

Two general comments
A.  first summing up the ORs 1 to 10 and then seeing for a trend (e.g.
with a meta-regression) is subject to Simpson's paradox. This is why
you need an approach like the on described in the cited paper.

B.  I'm not sure how metap could help you.  -metap- does a
meta-analysis of significance levels, a whole family of non-parametric
meta-analysis methods (metap implements 3 of numerous approaches).
This is essentially an omnibus test and therefore does not have the
interpretation you would wish. A meta-analysis of p-values asks is
there evidence of significant deviation from the null in AT LEAST ONE
of the studies?  A typical misinterpretaion of metap results is that
this is the p-value for the overall summary effect.


hope these thoughts help

tom



On Dec 21, 2007 3:52 PM, Jayaprakash, Vijay
<[email protected]> wrote:
> Hi Stata users,
>        I'm trying to do a meta analysis of data from 10 different studies. The smoking variable in each study is stratified into categories (Category 1:1-10 cigarettes, Category 2: 10-20 cigs, Category3: 20-30 cigs etc.). I calculated the OR for each category (of smoking) by study.  I then did a meta analysis and calculated the OR for each category by random effects model using the meta command:
> meta  or1 lcl1 ucl1, ci eform
> meta  or2 lcl2 ucl2, ci eform
>
> I found that metap command can provide the p-value for each category (from p-values of each study for that specific category). Is there a way to get the p for trend BETWEEN the categories from the random effects estimate? I would like to report from the meta-analysis results if there is a dose-response relationship of smoking to the disease and if so what the p for trend is.
>
> I will very much appreciate your help.
>
> Thanks
>
> Vijay
>
>
>
>
>
>
>
> This email message may contain legally privileged and/or confidential information.  If you are not the intended recipient(s), or the employee or agent responsible for the delivery of this message to the intended recipient(s), you are hereby notified that any disclosure, copying, distribution, or use of this email message is prohibited.  If you have received this message in error, please notify the sender immediately by e-mail and delete this email message from your computer. Thank you.
>
> *
> *   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/
>
*
*   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/



© Copyright 1996–2024 StataCorp LLC   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index