Evidence map›Paper›PMID 17244367›Full record

ArticleBMC medical research methodology2007

Inclusion of zero total event trials in meta-analyses maintains analytic consistency and incorporates all available data.

Jan O Friedrich, Neill K J Adhikari, Joseph Beyene

Abstract read
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In one paragraph

Article in BMC medical research methodology, 2007. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 176 papers, 116 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
176citing papers in PubMed, 116 pooled it
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

176 citing papers in PubMed, 116 syntheses or guidelines pooled it.

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  14. Examining the role of smoking on clinical outcomes after arthroscopic surgery of the hip: a systematic review and meta-analysis.European journal of orthopaedic surgery & traumatology : orthopedie traumatologie · 2024
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116 more citing papers are in PubMed but not listed here.

4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

3 authors.

Jan O FriedrichInterdepartmental Division of Critical Care, University of Toronto, Toronto, Canada. j.friedrich@utoronto.ca
Neill K J Adhikari
Joseph Beyene

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundMeta-analysis handles randomized trials with no outcome events in both treatment and control arms inconsistently, including them when risk difference (RD) is the effect measure but excluding them when relative risk (RR) or odds ratio (OR) are used. This study examined the influence of such trials on pooled treatment effects.

methodsAnalysis with and without zero total event trials of three illustrative published meta-analyses with a range of proportions of zero total event trials, treatment effects, and heterogeneity using inverse variance weighting and random effects that incorporates between-study heterogeneity.

resultsIncluding zero total event trials in meta-analyses moves the pooled estimate of treatment effect closer to nil, decreases its confidence interval and decreases between-study heterogeneity. For RR and OR, inclusion of such trials causes small changes, even when they comprise the large majority of included trials. For RD, the changes are more substantial, and in extreme cases can eliminate a statistically significant effect estimate.

conclusionTo include all relevant data regardless of effect measure chosen, reviewers should also include zero total event trials when calculating pooled estimates using OR and RR.

Indexed as

Meta-Analysis as TopicHumansRandomized Controlled Trials as TopicStatistics as Topic

Identifiers

PMID17244367
PMCPMC1783664

What OpenQuestion holds

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Read underepoch 390

Registered trials

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.