Evidence map›Paper›PMID 22334559›Full record

SynthesisBMJ (Clinical research ed.)2012

Impact of single centre status on estimates of intervention effects in trials with continuous outcomes: meta-epidemiological study.

Aïda Bafeta, Agnes Dechartres, Ludovic Trinquart, Amélie Yavchitz, Isabelle Boutron, Philippe Ravaud

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

Synthesis in BMJ (Clinical research ed.), 2012. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 64 papers, 25 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
64citing papers in PubMed, 25 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

64 citing papers in PubMed, 25 syntheses or guidelines pooled it.

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  14. Interventions for treating leg ulcers in people with sickle cell disease.The Cochrane database of systematic reviews · 2021
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4 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

6 authors.

Aïda BafetaINSERM U738, Paris, France.
Agnes Dechartres
Ludovic Trinquart
Amélie Yavchitz
Isabelle Boutron
Philippe Ravaud

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

objectiveTo compare estimates of intervention effects between single centre and multicentre randomised controlled trials with continuous outcomes.

designMeta-epidemiological study. DATA SOURCES: 26 meta-analyses totalling 292 randomised controlled trials (177 single centre, 115 multicentre) with continuous outcomes published between January 2007 and January 2010 in the Cochrane database of systematic reviews. DATA EXTRACTION: Data were extracted on characteristics of trials, single or multicentre status, risk of bias using the risk of bias tool of the Cochrane Collaboration, and results. DATA SYNTHESIS: The intervention effects were estimated with standardised mean differences. For each meta-analysis, random effects meta-regression was used to estimate the difference in standardised mean differences between single centre and multicentre trials. Differences in standardised mean differences were then pooled across meta-analyses by a random-effects meta-analysis model. A combined difference in standardised mean differences of less than 0 indicated that single centre trials showed larger treatment effects, on average, than did multicentre trials. Because single centre trials may be more prone to publication bias and may have lower methodological quality than multicentre trials, sensitivity analyses were done with adjustment for sample size and domains of the risk of bias tool.

resultsSingle centre trials showed larger intervention effects than did multicentre trials (combined difference in standardised mean differences -0.09, 95% confidence interval -0.17 to -0.01, P=0.04), with low heterogeneity across individual meta-analyses (I(2)=0%, between meta-analyses variance τ(2)=0.00). Adjustment for sample size slightly attenuated the difference (-0.08, -0.17 to 0.01). Adjustment for risk of bias yielded similar estimates with wider confidence intervals, some of them crossing 0 (-0.09, -0.17 to 0.00 for overall risk of bias).

conclusionsOn average, single centre clinical trials with continuous outcomes showed slightly larger intervention effects than did multicentre trials. Further research is needed to investigate potential causes of these differences.

Indexed as

BiasEffect Modifier, EpidemiologicMulticenter Studies as TopicMeta-Analysis as TopicRandomized Controlled Trials as Topic

Identifiers

PMID22334559
PMCPMC3279328

What OpenQuestion holds

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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.