[R-meta] Accounting for baseline differences in meta-analysis

[Michael Dewey]

Dear Gladys

If I understand this correctly in a randomised study you can analyse the 
post treatment values alone or take into account any baseline value you 
wish. You may get a more precise result if you adjust for baseline.

Michael

On 02/02/2021 08:57, Gladys Barragan-Jason wrote:
> Dear Gerta,
> Thanks for your response. I also realized that most of the time papers 
> do not report the pre-treatment and/or the pre-control values. Sometimes 
> they just say that the values are not different but do not report 
> thoses, but more often they do not measure it at all.  Is there any way 
> to take this into account?...I am not sure about how to deal with 
> presence vs. absence of such values in the meta-analysis or whether this 
> just needs to be discussed as a potential limitation.
> Thanks a lot for your response.
> Gladys
> 
> Le jeu. 28 janv. 2021 à 12:35, Dr. Gerta Rücker 
> <ruecker using imbi.uni-freiburg.de <mailto:ruecker using imbi.uni-freiburg.de>> a 
> écrit :
> 
>     Dear Gladys,
> 
>     An obvious approach would be to take the post values (or,
>     equivalently, the change scores) as an outcome, and the baseline
>     values as a covariate in a metaregression model.
> 
>     Best,
> 
>     Gerta
> 
>     Am 28.01.2021 um 10:49 schrieb Gladys Barragan-Jason:
>>     Dear all,
>>     I would like to know how to take the baseline difference into
>>     account in meta-analysis of the impact of a treatment on
>>     experimental data in which the baseline of the control group is
>>     different from the baseline of the treatment.
>>     For now, I am using the post- means and SD of the control and the
>>     treatment group (and the rma.mv <http://rma.mv> function) and also
>>     the pre-post values of the treatment group but I don't think this
>>     is correct and I am not sure how to proceed.
>>     Any advice?
>>     Thanks a lot in advance.
>>     Best regards,
>>     Gladys
>>
>>     -- 
>>
>>     ------------------------------------------
>>
>>     Gladys Barragan-Jason, PhD.  Website
>>     <https://sites.google.com/view/gladysbarraganjason/home>
>>
>>     Station d'Ecologie Théorique et Expérimentale (SETE)
>>
>>     CNRS de Moulis
>>
>>     image.pngimage.png
>>
>>
>>
>>
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> 
> 
> 
> -- 
> 
> ------------------------------------------
> 
> Gladys Barragan-Jason, PhD. ____ Website 
> <https://sites.google.com/view/gladysbarraganjason/home>
> 
> Station d'Ecologie Théorique et Expérimentale (SETE)____
> 
> CNRS de Moulis____
> 
> image.pngimage.png____
> 
> 
> 
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-- 
Michael
http://www.dewey.myzen.co.uk/home.html