Evidence map›Paper›PMID 20042080›Full record

ArticleBMC medical research methodology2009

Estimating required information size by quantifying diversity in random-effects model meta-analyses.

Jørn Wetterslev, Kristian Thorlund, Jesper Brok, Christian Gluud

Registry-linked trialAbstract read
PubMed Full text at PMC Publisher
In one paragraph

Article in BMC medical research methodology, 2009. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT04801238 (preGallstep), which is not on this map. Cited by 439 papers, 114 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
439citing papers in PubMed, 114 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.

NCT04801238 naunknown statusnot on this mapstarted 2021, after this paper: background citation

preGallstep: One-step Laparoscopic Cholecystectomy, Common Bile Duct Exploration and Stone Extraction Versus Two-step Endoscopic Retrograde Cholangiography and Stone Extraction Plus Laparoscopic Cholecystectomy for Common Bile Duct Stones

TypeinterventionalSponsorLars Tue SorensenRan2021 to 2024Enrolled150ConditionsPancreatitis, Cholangitis, Cholecystitis, GallstoneArmsLCBDE + LC, ERC + LC
3 · Its place in the literature

Who cites it

439 citing papers in PubMed, 114 syntheses or guidelines pooled it.

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  5. Liver support systems for adults with acute liver failure.The Cochrane database of systematic reviews · 2026
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  8. Corticosteroids for treatment of leptospirosis.The Cochrane database of systematic reviews · 2025
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  11. Entecavir for children and adults with chronic hepatitis B.The Cochrane database of systematic reviews · 2025
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  20. Statins for the primary prevention of venous thromboembolism.The Cochrane database of systematic reviews · 2024
    Pooled it

379 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

4 authors.

Jørn WetterslevCopenhagen Trial Unit, Centre for Clinical Intervention Research, Department 3344, Rigshospitalet, Copenhagen University Hospital, Blegdamsvej 9, DK-2100 Copenhagen Ø, Denmark. Wetterslev@ctu.rh.dk
Kristian Thorlund
Jesper Brok
Christian Gluud

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundThere is increasing awareness that meta-analyses require a sufficiently large information size to detect or reject an anticipated intervention effect. The required information size in a meta-analysis may be calculated from an anticipated a priori intervention effect or from an intervention effect suggested by trials with low-risk of bias.

methodsInformation size calculations need to consider the total model variance in a meta-analysis to control type I and type II errors. Here, we derive an adjusting factor for the required information size under any random-effects model meta-analysis.

resultsWe devise a measure of diversity (D2) in a meta-analysis, which is the relative variance reduction when the meta-analysis model is changed from a random-effects into a fixed-effect model. D2 is the percentage that the between-trial variability constitutes of the sum of the between-trial variability and a sampling error estimate considering the required information size. D2 is different from the intuitively obvious adjusting factor based on the common quantification of heterogeneity, the inconsistency (I2), which may underestimate the required information size. Thus, D2 and I2 are compared and interpreted using several simulations and clinical examples. In addition we show mathematically that diversity is equal to or greater than inconsistency, that is D2 >or= I2, for all meta-analyses.

conclusionWe conclude that D2 seems a better alternative than I2 to consider model variation in any random-effects meta-analysis despite the choice of the between trial variance estimator that constitutes the model. Furthermore, D2 can readily adjust the required information size in any random-effects model meta-analysis.

Indexed as

Meta-Analysis as TopicSample SizeRandomized Controlled Trials as TopicStatistics as Topic

Identifiers

PMID20042080
PMCPMC2809074

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Registered trials

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.