Evidence map›Paper›PMID 37606180›Full record

SynthesisResearch synthesis methods2023

Two-stage or not two-stage? That is the question for IPD meta-analysis projects.

Richard D Riley, Joie Ensor, Miriam Hattle, Katerina Papadimitropoulou, Tim P Morris

Abstract readMeta-Analysis
PubMed Full text at PMC Publisher
In one paragraph

Synthesis in Research synthesis methods, 2023. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 31 papers, 16 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
31citing papers in PubMed, 16 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

31 citing papers in PubMed, 16 syntheses or guidelines pooled it.

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  7. Risk Factors for Adverse Pregnancy Outcomes in Reduced Fetal Movement: An IPD Meta-Analysis.BJOG : an international journal of obstetrics and gynaecology · 2025
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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

5 authors.

Richard D RileyInstitute of Applied Health Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK.ORCID https://orcid.org/0000-0001-8699-0735
Joie EnsorInstitute of Applied Health Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK.ORCID https://orcid.org/0000-0001-7481-0282
Miriam HattleInstitute of Applied Health Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK.ORCID https://orcid.org/0000-0003-1542-6277
Katerina PapadimitropoulouHealth Economics and Market Access, Amaris Consulting, Lyon, France.ORCID https://orcid.org/0000-0002-5732-4044
Tim P MorrisMRC Clinical Trials Unit at UCL, Institute of Clinical Trials and Methodology, UCL, London, UK.ORCID https://orcid.org/0000-0001-5850-3610

Funding

Medical Research Council MC_UU_00004/06Medical Research Council MC_UU_00004/07
6 · The paper itself

Abstract

Individual participant data meta-analysis (IPDMA) projects obtain, check, harmonise and synthesise raw data from multiple studies. When undertaking the meta-analysis, researchers must decide between a two-stage or a one-stage approach. In a two-stage approach, the IPD are first analysed separately within each study to obtain aggregate data (e.g., treatment effect estimates and standard errors); then, in the second stage, these aggregate data are combined in a standard meta-analysis model (e.g., common-effect or random-effects). In a one-stage approach, the IPD from all studies are analysed in a single step using an appropriate model that accounts for clustering of participants within studies and, potentially, between-study heterogeneity (e.g., a general or generalised linear mixed model). The best approach to take is debated in the literature, and so here we provide clearer guidance for a broad audience. Both approaches are important tools for IPDMA researchers and neither are a panacea. If most studies in the IPDMA are small (few participants or events), a one-stage approach is recommended due to using a more exact likelihood. However, in other situations, researchers can choose either approach, carefully following best practice. Some previous claims recommending to always use a one-stage approach are misleading, and the two-stage approach will often suffice for most researchers. When differences do arise between the two approaches, often it is caused by researchers using different modelling assumptions or estimation methods, rather than using one or two stages per se.

Indexed as

ResearchCluster AnalysisHumansLinear Modelsindividual participant data (IPD)meta-analysisone-stage approachtwo-stage approach

Identifiers

PMID37606180
PMCPMC7615283

What OpenQuestion holds

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LicenceCC BY
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Registered trials

None linked

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.