Evidence map›Paper›PMID 26068945›Full record

ArticlePharmacoEconomics2015

Evaluating the Generalisability of Trial Results: Introducing a Centre- and Trial-Level Generalisability Index.

Adrian Gheorghe, Tracy Roberts, Karla Hemming, Melanie Calvert

Abstract read
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In one paragraph

Article in PharmacoEconomics, 2015. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 7 papers, 2 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
7citing papers in PubMed, 2 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

7 citing papers in PubMed, 2 syntheses or guidelines pooled it.

  1. Pooled it
  2. Pooled it
  3. Trial
  4. Article
  5. Article
  6. Review
  7. Article
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.

Adrian GheorghePrimary Care Clinical Sciences and MRC Midlands Hub for Trials Methodology Research, University of Birmingham, Birmingham, UK. adrian.e.gheorghe@gmail.com.
Tracy RobertsHealth Economics Unit, University of Birmingham, Birmingham, UK.
Karla HemmingPublic Health, Epidemiology and Statistics, University of Birmingham, Birmingham, UK.
Melanie CalvertPrimary Care Clinical Sciences and MRC Midlands Hub for Trials Methodology Research, University of Birmingham, Birmingham, UK.

Funding

Department of Health WMCLAHRC-2014-1Medical Research Council G0800808
6 · The paper itself

Abstract

backgroundFew randomised controlled trials (RCTs) recruit centres representatively, which may limit the external validity of trial results.

objectiveThe aim of this study was to propose a proof-of-concept method of assessing the generalisability of the clinical and cost-effectiveness findings of a given RCT.

methodsWe developed a generalisability index (Gix), informed by centre-level characteristics, as a measure of centre and trial representativeness. The centre-level Gix quantifies how representative a centre is in relation to its jurisdiction, e.g. a country or health authority. The trial-level Gix quantifies how representative trial recruitment is in relation to clinical practice in the jurisdiction. Taking a real-world RCT as a case study and assuming trial-wide results to represent 'true jurisdiction values', we used simulation methods to recreate 5000 RCTs and investigate the relationship between trial representativeness, reflected by the standardised trial-Gix, and the deviation of simulated trial results from the 'true values'.

resultsThe simulation study provides evidence that trial results (odds ratio for the primary outcome and incremental quality-adjusted life-years) were influenced by the representativeness of the sample of recruiting centres. Simulated RCTs with the closest results to the 'true values' were those whose recruitment closely mirrored the jurisdiction-wide context. Results appeared robust to six alternative specifications of the Gix.

conclusionsOur findings suggest that an unrepresentative selection of centres limits the external validity of trial results. The Gix may be a valuable tool to help facilitate rational selection of trial centres and ensure the generalisability of results at the jurisdiction level.

Indexed as

Health FacilitiesModels, TheoreticalClinical Trials, Phase III as TopicCost-Benefit AnalysisHumansRandomized Controlled Trials as TopicSampling StudiesTreatment Outcome

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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.