[R-meta] Inconsistency Testing

[Gerta Ruecker]

Dear Sean,

You might try R package netmeta, functions netmeta() and netcomb() that 
have been developed perfectly for your situation 
https://cran.r-project.org/web/packages/netmeta/index.html. For the 
theory see https://onlinelibrary.wiley.com/doi/10.1002/bimj.201800167 
and also the seminal paper 
https://academic.oup.com/aje/article/169/9/1158/125216 .

Attached you find a presentation from our teaching in Freiburg, also 
including some R code. Hope this is helpful.

Best,

Gerta


Am 09.03.2021 um 23:57 schrieb Sean:
> Hi Dr. Rücker,
>
> - Let A, B, C, D be some fungicides, do I understand it correctly that
> treatments are combinations in the sense of A+B, A+C+D, A+B+C etc.?
>
> *Yes, that is correct. *
>
> - In each trial, several of these combinations are compared?
>
> *Yes. *
>
> - "Design" is meant to be the notion in network meta-analysis, thus "A
> vs A+B vs A+B+C" would be a possible design?
>
> *Yes I think you have it, for example, trial 1 had A+B, A+C+D, and 
> A+B+C as its treatments and trial 2 had A+C, A+D, and A+C+D, and so on. *
>
> Which R package do you use?
>
> *metafor*
> *
> *
> Best,
>
> Sean
>
>
> On Tue, Mar 9, 2021 at 5:47 PM Dr. Gerta Rücker 
> <ruecker using imbi.uni-freiburg.de <mailto:ruecker using imbi.uni-freiburg.de>> 
> wrote:
>
>     Dear Sean,
>
>     At first, I have to understand your problem. You mention
>     treatments that
>     are combinations of fungicides, and you mention designs. To clarify
>     these notions, my questions are:
>
>     - Let A, B, C, D be some fungicides, do I understand it correctly
>     that
>     treatments are combinations in the sense of A+B, A+C+D, A+B+C etc.?
>
>     - In each trial, several of these combinations are compared?
>
>     - "Design" is meant to be the notion in network meta-analysis,
>     thus "A
>     vs A+B vs A+B+C" would be a possible design?
>
>     (A different possibility is that you do not have combinations of
>     treatments in the sense above, but - simpler - different designs
>     such as
>     A, B, C in one trial and A, C, D in another trial.)
>
>     Could you clarify these notions?
>
>     Which R package do you use?
>
>     Best,
>
>     Gerta
>
>     Am 09.03.2021 um 23:22 schrieb Sean:
>     > Hello everyone,
>     >
>     >
>     > I’ve been stuck on a question about inconsistency testing for quite
>     > some time, but first a little simplified background:
>     >
>     >
>     > I’ve calculated effect sizes for all treatments from 50 independent
>     > trials conducted over the past 10 years. These treatments are
>     > different fungicides applied to a plant to control a foliar
>     pathogen.
>     > Throughout those 10 years, researchers tested 20 different products,
>     > and a treatment (4-15 per trial) is different combinations of
>     usually
>     > 1-6 of those fungicides. There was no coordination over those 10
>     years
>     > in experimental design, so no treatment was truly replicated.
>     Instead,
>     > what I’ve done is reduce treatments into larger categories based on
>     > the modes of action of those fungicides. This has allowed me to have
>     > enough similarly coded treatments to perform a network
>     meta-analysis.
>     > That went all well and good, however, when it comes to inconsistency
>     > testing, I have as many study designs as I have studies. 50
>     > independent trials, 50 designs.
>     >
>     >
>     > Can I even technically perform inconsistency testing? What I've read
>     > in the literature doesn't seem to account for my situation. If not,
>     > what does this mean for my meta-analysis? Do I truly need to perform
>     > inconsistency testing?
>     >
>     >
>     > Thank you all for your time, hope your week is going well!
>     >
>     >
>     > Sean
>     >
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>
-- 

Dr. rer. nat. Gerta Rücker, Dipl.-Math.

Institute of Medical Biometry and Statistics,
Faculty of Medicine and Medical Center - University of Freiburg

Stefan-Meier-Str. 26, D-79104 Freiburg, Germany

Phone:    +49/761/203-6673
Fax:      +49/761/203-6680
Mail:     ruecker using imbi.uni-freiburg.de
Homepage: https://www.uniklinik-freiburg.de/imbi-en/employees.html?imbiuser=ruecker


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