[R-meta] [netmeta] Error message in network meta-analysis: "Problem with multi-arm studies: Studies with inconsistent treatment estimates"
ruecker @end|ng |rom |mb|@un|-|re|burg@de
Fri Feb 7 19:47:08 CET 2020
Please always respond to the mailing list.
In fact, Guido is right and you should calculate the SMDs for the
three-arm studies in the way he described.
Am 07.02.2020 um 18:42 schrieb Rogasch, Rebecca Manuela Madeleine:
> Dear Gerta,
> many thanks for the quick Response!
> I'll be glad to send additional infomation.
> In case the error message is related to my calculations of effect
> sizes in the 3-arm-studies
> the Output attatched might help to identify the source of the Problem.
> (I haven't merged the Information of other variables yet [not relevant
> here], which is why there are lots of missings for the 3-arm studies)
> Best regards,
> *Von:* Gerta Ruecker <ruecker using imbi.uni-freiburg.de>
> *Gesendet:* Freitag, 7. Februar 2020 17:36:16
> *An:* Rogasch, Rebecca Manuela Madeleine;
> r-sig-meta-analysis using r-project.org
> *Betreff:* Re: [R-meta] [netmeta] Error message in network
> meta-analysis: "Problem with multi-arm studies: Studies with
> inconsistent treatment estimates"
> Dear Rebecca,
> First to the theoretical background of this error message: If you have
> a three-arm study, treatment effects within the study must be
> consistent. This means that for three arms A, B, C you have mean
> values x_A, x_B, x_C of your score. The contrasts (differences) then are
> * for A vs B: d_AB = x_A - x_B
> * for A vs C: d_AC = x_A - x_C
> * for B vs C: d_BC = x_B - x_C
> That is, you have relations between the three contrasts, e.g., d_AC =
> d_AB + d_BC. If the data do not fulfill these relations, an error
> message is given.
> However, I have a problem with understanding your data structure, and
> thus I don't fully understand how this can happen in your case. You
> say you have three-arm studies, but how are they entered?
> Unfortunately, the first three studies in your extract of the data are
> all two-arm. How do the three-arm studies look in the data?
> It would be easier to help if we could see the whole data set or at
> least data for a three-arm study.
> Am 07.02.2020 um 16:42 schrieb Rogasch, Rebecca Manuela Madeleine:
>> Dear experts,
>> I'm seeking advice regarding an error message in network meta-analysis using the netmeta package.
>> To briefly outline the objective and describe the data structure:
>> I am conducting a network meta-analysis on the effectiveness of PTSD intervention programs.
>> The primary outcome is the PTSD total symptom score (=continuous outcome).
>> All studies are randomized-controlled trials. There are 8 three-arm studies in my data set and 64 two-arm studies.
>> I calculated the SMD (post-post) from means and SDs.
>> Here is an example for the data structure:
>> studlab sampleID OutcID TR1 TR2 Mt2TR1 SDt2TR1 Mt2TR2 SDt2TR2 n_TR1 n_TR2 n_total smd se
>> 1 101 10101 EMDR WL 22.87 20.27 54.21 16.26 15 14 29 -1.65 0.19
>> 100 10001 1000101 NET WL 55.07 27.01 76.86 17.14 19 19 38 -0.94 0.12
>> 104 10401 1040101 NET PsEd 19.10 11.70 21.20 9.40 17 12 29 -0.19 0.14
>> When applying the netmeta function I get the following error message:
>>> mn1 <- netmeta(smd, se, TR1, TR2, studlab, data=dat3, sm="SMD", comb.random=TRUE)
>> Error: Problems in multi-arm studies!
>> - Studies with inconsistent treatment estimates: '107', '121', '130', '15', '22', '34', '36', '87'
>> - Please check original data used as input to netmeta().
>> - For more details, re-run netmeta() with argument details.chkmultiarm = TRUE.
>> - Argument 'tol.multiarm' in netmeta() can be used to relax consistency
>> assumption for multi-arm studies (if appropriate).
>> My questions are as follows:
>> 1. I am not able to make sense of the error message regarding inconsistency within the 3-arm-studies. Can anyone help?
>> 2. When setting the argument tol.multiarm = 0.05 it runs without any error message.
>> However, I am not sure what the argument does, exactly, and haven't been able to find any detailed information.
>> Does anyone know what the argument does or where I can find further information?
>> Looking forward to hearing from you!
>> Best regards,
>> [[alternative HTML version deleted]]
>> R-sig-meta-analysis mailing list
>> R-sig-meta-analysis using r-project.org
> Dr. rer. nat. Gerta R�cker, 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
Dr. rer. nat. Gerta R�cker, 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
Mail: ruecker using imbi.uni-freiburg.de
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