[R-meta] [netmeta] Error message in network meta-analysis: "Problem with multi-arm studies: Studies with inconsistent treatment estimates"

[Gerta Ruecker]

Dear Rebecca,


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.


Best,

Gerta




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,
>
> Rebecca
>
> ------------------------------------------------------------------------
> *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.
>
> Best,
>
> Gerta
>
>
> 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,
>> Rebecca
>>
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>>
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> -- 
>
> 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
> Homepage:https://www.imbi.uni-freiburg.de/persons/ruecker/person_view

-- 

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
Homepage: https://www.imbi.uni-freiburg.de/persons/ruecker/person_view


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