[R-meta] Question metafor network meta-analysis with multiple time points

[Viechtbauer, Wolfgang (NP)]

Dear Gerjon,

Can you show what your data structure looks like? You don't have to show the actual data, but it would help to know how the data are structured. Like:

Study Time Trt
--------------
?     ?    ?
...

And are you using a contrast- or an arm-based approach for conducting your network meta-analysis?

Best,
Wolfgang

> -----Original Message-----
> From: R-sig-meta-analysis <r-sig-meta-analysis-bounces using r-project.org> On Behalf
> Of Gerjon Hannink via R-sig-meta-analysis
> Sent: Wednesday, November 20, 2024 16:25
> To: r-sig-meta-analysis using r-project.org
> Cc: Gerjon Hannink <gerjonhannink using gmail.com>
> Subject: [R-meta] Question metafor network meta-analysis with multiple time
> points
>
> Hi all,
>
> I have a `metafor` question, and hope you can help me out. I was
> thinking of (and struggling with) how I would do a network
> meta-analysis with studies with measurements at multiple time points
> using `rma.mv` from the `metafor` -package. Would that be possible?
>
> In many presentations (e.g. provided on
> https://www.wvbauer.com/doku.php/presentations) I find 'multiple time
> points' and 'network meta-analysis'. In these examples, the following
> is used, e.g.,
>
> `res <- rma.mv(yi, V, mods = ~ factor(time) - 1, data = dat.long,
> random = ~ time | study, struct = "HAR")` and
> `res <- rma.mv(yi, vi, mods = ~ trt, data = dat, random = ~ 1 |
> study/trt)`, respectively.
>
> Would it be as simple as just combining the two? I guess it is not
> that simple...
>
> I played a bit using something like:
>
> rma.mv(yi, V, mods = ~ factor(time) * trt , data = dat.long, random =
> ~ time | study/trt)
>
> But this returned an error message 'Cannot use '~ inner |
> outer1/outer2' type terms in the 'random' argument'.
> I guess I would also need to modify V a bit to take all necessary
> variances/covariance into account...
> And what about `struct`?
>
> Thanks for your help & looking forward to hearing your thoughts!
>
> Best regards,
> Gerjon