[R-meta] meta-analysis of 0 events in one or both arms

[Gerta Ruecker]

Dear Nicky, dear Irene,

As outlined in my first post, it is not true that single-zero studies 
can be included without continuity methods only with Bayesian methods.

The Mantel-Haenszel method is a very simple and also intuitive way to 
include them. If you denote the four entries of a 2x2 table by a,b,c,d, 
the formula (here OR) is

OR.pooled = sum(a*d)/sum(b*c)

If, for example, one of the a's is zero, but not the corresponding c, 
this summand becomes zero in the numerator, but not in the denominator. 
Thus the study is included, and the estimator is well defined, except 
all denominators are zero (no events at all in the second group).

A double-zero is excluded (and does not contribute to the likelihood).

Best,

Gerta

Am 03.04.2020 um 11:35 schrieb Nicky Welton:
> Dear Irene,
>
> If there are 0's on both arms then that study should be excluded from the analysis in my opinion. The study is not large enough to measure the outcome in question, and the results are equally consistent with an OR of 0.5, 1, or 2, etc.
> For the studies with a 0 on one arm. The only way to incorporate these without a continuity correction is to use a Bayesian analysis where exact binomial likelihoods are given. Even then depending on your evidence structure, it may still be necessary to add a continuity correction to obtain convergence.
>
> Best wishes,
>
> Nicky
>
>
>   
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Nicky J. Welton
> Professor of Statistical and Health Economic Modelling
> Director of the NICE Technical Support Unit
>   
> Population Health Sciences, Bristol Medical School
> University of Bristol
> Canynge Hall, 39 Whatley Road
> Bristol. BS8 2PS
> UK
>   
> Tel: +44(0)117 3313918
> Email: Nicky.Welton using bristol.ac.uk
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> A top 10 UK university and top 50 world university (QS Rankings 2020)
> A top 2 UK university with leading employers (High Fliers 2019)
> A top 5 UK university for research (THE analysis of REF 2014)
> A top 6 European university for teaching (THE 2018)
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
>
> -----Original Message-----
> From: R-sig-meta-analysis <r-sig-meta-analysis-bounces using r-project.org> On Behalf Of Bighelli, Irene
> Sent: 03 April 2020 09:16
> To: r-sig-meta-analysis using r-project.org
> Subject: [R-meta] meta-analysis of 0 events in one or both arms
>
> Dear all,
>
> I am dealing with meta-analysis and network meta-analysis of dichotomous data where the number of event in one or both arms is = 0. I would like to find a way to include these studies in the analysis, without applying a continuity correction. Is it possible?
>
> I know there are different ways to deal with this,
>
> in metabin: I understand that a continuity correction is applied by default (https://cran.r-project.org/web/packages/meta/meta.pdf page 60-62<https://cran.r-project.org/web/packages/meta/meta.pdf%20page%2060-62>): "For studies with a zero cell count, by default, 0.5 is added to all cell frequencies of these studies; if incr is "TACC" a treatment arm continuity correction is used instead (Sweeting et al., 2004; Diamond et al., 2007). For odds ratio and risk ratio, treatment estimates and standard errors are only calculated for studies with zero or all events in both groups if allstudies is TRUE." Does it mean that with allstudies=TRUE only studies with zero events are counted, and the ones with some events excluded?
>
> in netmeta: I read in the manual of the pairwise function (https://cran.r-project.org/web/packages/netmeta/netmeta.pdf), where the argument "allstudies=TRUE" allows to include in the calculations such studies ("A logical indicating if studies with zero or all events in two treatment arms are to be included in the meta-analysis"). However, I was not able to find a description of how this works, and whether it applies a continuity correction.
>
>
> Thanks a lot in advance for your help,
>
> Irene
>
> ________________
> Irene Bighelli  PhD
>
> Technical University of Munich | School of Medicine | Klinikum rechts der Isar
>
> Department of Psychiatry and Psychotherapy
>
> Section for Evidence Based Medicine in Psychiatry
>
> Ismaningerstr. 22, 81675 M�nchen, Germany
>
> Tel: +4908941404243
>
> Mail: irene.bighelli using tum.de<mailto:irene.bighelli using tum.de>
>
>
> 	[[alternative HTML version deleted]]
>
> _______________________________________________
> R-sig-meta-analysis mailing list
> R-sig-meta-analysis using r-project.org
> https://stat.ethz.ch/mailman/listinfo/r-sig-meta-analysis

-- 

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.imbi.uni-freiburg.de/persons/ruecker/person_view