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

Nicky Welton N|cky@We|ton @end|ng |rom br|@to|@@c@uk
Fri Apr 3 11:35:42 CEST 2020

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 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
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Bristol. BS8 2PS
Tel: +44(0)117 3313918
Email: Nicky.Welton using bristol.ac.uk
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-----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 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>

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