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st: Question regarding Trim and Fill method using 'metatrim'


From   Chan Yoon <yoon.chan.alex@gmail.com>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   st: Question regarding Trim and Fill method using 'metatrim'
Date   Sat, 4 Sep 2010 12:02:27 +0900

> Hi. I am having trouble using stata in meta-analysis.
>  
> I have used total 13 studies in my meta-analysis usig Random-effects model. Pulled estimate was 0.852  with 95% confidene interval (0.762 - 0.952)
> using Egger's test, p value is 0.174 which suggests publication bias with little statistical significance.
> however,although little publication bias in Egger;s test, funnel plot looked somewhat asymmetric so we decided to use Trim and Fill method to attain adjusted estimate.
>  
>    using commend as follows
>  
> metatrim rr ll ul, ci eform reffect
>  
>    and result came out as follows
>  
> Note: option 'ci' specified.
> Meta-analysis
>  
>             |  Pooled      95% CI         Asymptotic      No. of
> Method |     Est   Lower   Upper  z_value  p_value   studies
> -------+----------------------------------------------------
> Fixed     |  -0.102  -0.151  -0.053   -4.120    0.000     13
> Random |  -0.160  -0.271  -0.050   -2.838    0.005
>  
> Test for heterogeneity: Q= 41.214 on 12 degrees of freedom (p= 0.000)
> Moment-based estimate of between studies variance =  0.023
>  
> Trimming estimator: Linear
> Meta-analysis type: Random-effects model
> iteration |  estimate    Tn    # to trim     diff
> ----------+--------------------------------------
>       1     |   -0.160     41         0          91
>       2     |   -0.160     41         0           0
> Note: no trimming performed; data unchanged
>  
> Filled 
> Meta-analysis (exponential form)
>             |  Pooled      95% CI         Asymptotic      No. of
> Method |     Est   Lower   Upper  z_value  p_value   studies
> -------+----------------------------------------------------
> Fixed     |   0.903   0.860   0.948   -4.120    0.000     13
> Random |   0.852   0.762   0.952   -2.838    0.005
> Test for heterogeneity: Q= 41.214 on 12 degrees of freedom (p= 0.000)
> Moment-based estimate of between studies variance =  0.023
>  
> -------------------------------------------------------------------------------------------------------------
>  
> I have used metatrim with other dataset before and it added some studies to reduce the asymmetric funnel plot.
> with additional studies filled meta-analysis showed publication bias adjusted pulled estimate.
>  
> However, using this dataset, to trimming performed and data unchanged. I think even egger;s test showes insignificant publication bias, there should be some cahnge in the estimate using trima nd fill method. so.. I believed there is something wrong in the way I used 'metatrim'.
>  
> I would really appreciate some help by experts. Thank you very much for readling this long question.
>  
>  
>  
>  
> 

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