Cited by 278Meta-analysis and systematic reviewsStatistical Methods in EpidemiologyStatistical Methods in Clinical Trials

The DOI matches its Crossref record; 66 of the 66 references it cites were found in a registry or an index; 2 of the 74 sources its claims cite were checked for support.

A framework for meta-analysis of prediction model studies with binary and time-to-event outcomes

Open access
Debray, Thomas PA, Damen, Johanna AAG, Riley, Richard D, Snell, Kym, Reitsma, Johannes B, Hooft, Lotty, Collins, Gary S, Moons, Karel GM·2019·Statistical Methods in Medical Research

Abstract

It is widely recommended that any developed—diagnostic or prognostic—prediction model is externally validated in terms of its predictive performance measured by calibration and discrimination. When multiple validations have been performed, a systematic review followed by a formal meta-analysis helps to summarize overall performance across multiple settings, and reveals under which circumstances the model performs suboptimal (alternative poorer) and may need adjustment. We discuss how to undertake meta-analysis of the performance of prediction models with either a binary or a time-to-event outcome. We address how to deal with incomplete availability of study-specific results (performance estimates and their precision), and how to produce summary estimates of the c-statistic, the observed:expected ratio and the calibration slope. Furthermore, we discuss the implementation of frequentist and Bayesian meta-analysis methods, and propose novel empirically-based prior distributions to improve estimation of between-study heterogeneity in small samples. Finally, we illustrate all methods using two examples: meta-analysis of the predictive performance of EuroSCORE II and of the Framingham Risk Score. All examples and meta-analysis models have been implemented in our newly developed R package “metamisc”.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

The paper provides a statistical framework for meta-analyzing the predictive performance of prediction models with binary or time-to-event outcomes, including methods to restore unreported performance estimates and to summarize discrimination and calibration. It illustrates the framework with EuroSCORE II and Framingham Risk Score meta-analyses and implements the methods in the R package “metamisc.”

Key findings

  • EuroSCORE II: summary c-statistic 0.79 (95% CI 0.76–0.81; 95% PI 0.68–0.87); summary O:E ratio 1.11 (95% CI 0.90–1.36; 95% PI 0.43–2.85); calibration slope could not be estimated.
  • Framingham Risk Score: summary c-statistic 0.69 (95% CI 0.66–0.71; 95% PI 0.59–0.77); summary O:E ratio 0.60 (95% CI 0.46–0.79; 95% PI 0.20–1.84); calibration slope 1.03 (95% CI 0.94–1.12; 95% PI 0.93–1.13) under ML Model 3.
  • Proposed empirically-based priors for between-study heterogeneity substantially improved estimation of the between-study standard deviation in small meta-analyses.
  • Bayesian estimation was recommended because frequentist methods may fail to produce reliable confidence or prediction intervals when validation studies are sparse.

Methods

  • The paper develops frequentist and Bayesian random-effects meta-analysis models for the logit c-statistic, log total O:E ratio, and calibration slope, including one-stage models and meta-regression for heterogeneity.
  • Empirical examples used 23 EuroSCORE II validations and Framingham Risk Score validations in male populations; Framingham meta-analyses included K=21 for c-statistic, K=17 for O:E ratio, and K=11 for calibration slope.
  • Missing c-statistics, standard errors, and O:E ratios were restored from reported quantities using formulas; analyses were implemented in the R package “metamisc” using “metafor” and JAGS, with Bayesian convergence assessed by potential scale reduction factor ≤1.05.

Limitations

  • The paper states that frequentist meta-analysis may suffer convergence issues and unreliable precision/heterogeneity estimates when validation studies are sparse; Hartung–Knapp intervals are too narrow with fewer than five studies, and prediction intervals have poor coverage in some settings.
  • The paper states that meta-regression has low power and may suffer ecological bias; calibration slope could not be estimated for EuroSCORE II because subgroup-specific event rates were not extracted and the slope was not directly provided.
  • Evident from the text: performance estimates are often poorly reported, requiring restoration and assumptions; time-to-event O:E analyses may require extrapolation when follow-up times differ; the empirical examples are reanalyses of existing reviews rather than new prospective validation studies.

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Integrity signals

Registry

Crossref · 10.1177/0962280218785504

Cites

66 of 66 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Figures

Figure 1. Estimation of τdiscr in small samples. Estimates of τdiscr for meta-analyses with K validation studies. Results are based on 23!/(K!(23-K)!) meta-analyses for EuroSCORE II, and on 21!/(K!(21-K)!) meta-analyses for the Framingham Risk Score. For Bayesian meta-analysis models, τ^discr represents the posterior median. The reference value (solid line) was obtained by adopting a Bayesian meta-analysis with uniform prior in the full set of 23 (for EuroSCORE II) or 21 (for the Framingham Risk Score) studies. Similar reference values were obtained for ML, REML and Bayes (Student-t). ML: Maximum likelihood estimation; REML: restricted maximum likelihood estimation; BAYES (Student-t): Bayesian estimation with τdiscr∼Student-t(0,0.5²,3)T[0,10]; BAYES (Uniform): Bayesian estimation with τdiscr∼Unif(0,2).
Figure 1. Estimation of τdiscr in small samples. Estimates of τdiscr for meta-analyses with K validation studies. Results are based on 23!/(K!(23-K)!) meta-analyses for EuroSCORE II, and on 21!/(K!(21-K)!) meta-analyses for the Framingham Risk Score. For Bayesian meta-analysis models, τ^discr represents the posterior median. The reference value (solid line) was obtained by adopting a Bayesian meta-analysis with uniform prior in the full set of 23 (for EuroSCORE II) or 21 (for the Framingham Risk Score) studies. Similar reference values were obtained for ML, REML and Bayes (Student-t). ML: Maximum likelihood estimation; REML: restricted maximum likelihood estimation; BAYES (Student-t): Bayesian estimation with τdiscr∼Student-t(0,0.5²,3)T[0,10]; BAYES (Uniform): Bayesian estimation with τdiscr∼Unif(0,2).CC BY-NC · PubMed Central
Figure 2. Estimation of τcal.OE in small samples. Estimates of τcal.OE for meta-analyses with K validation studies. Results are based on 23!/(K!(23-K)!) meta-analyses for EuroSCORE II and on 17!/(K!(17-K)!) meta-analyses for the Framingham Risk Score. For Bayesian meta-analysis models, τ^cal.OE represents the posterior median. The reference value (solid line) was obtained by adopting a Bayesian meta-analysis with uniform prior in the full set of 23 (for EuroSCORE II) or 17 (for the Framingham Risk Score) studies. Similar reference values were obtained for ML, REML and Bayes (Student-t). ML: maximum likelihood estimation; REML: restricted maximum likelihood estimation; BAYES (Student-t): Bayesian estimation with τcal.OE∼Student-t(0,1.5²,3)T[0,10]; BAYES (Uniform): Bayesian estimation with τcal.OE∼Unif(0,2).
Figure 2. Estimation of τcal.OE in small samples. Estimates of τcal.OE for meta-analyses with K validation studies. Results are based on 23!/(K!(23-K)!) meta-analyses for EuroSCORE II and on 17!/(K!(17-K)!) meta-analyses for the Framingham Risk Score. For Bayesian meta-analysis models, τ^cal.OE represents the posterior median. The reference value (solid line) was obtained by adopting a Bayesian meta-analysis with uniform prior in the full set of 23 (for EuroSCORE II) or 17 (for the Framingham Risk Score) studies. Similar reference values were obtained for ML, REML and Bayes (Student-t). ML: maximum likelihood estimation; REML: restricted maximum likelihood estimation; BAYES (Student-t): Bayesian estimation with τcal.OE∼Student-t(0,1.5²,3)T[0,10]; BAYES (Uniform): Bayesian estimation with τcal.OE∼Unif(0,2).CC BY-NC · PubMed Central
Figure 3. Meta-analysis estimates for EuroSCORE II.
Figure 3. Meta-analysis estimates for EuroSCORE II.CC BY-NC · PubMed Central
Figure 4. Results from random-effects meta-regression models for the Framingham Risk Score (validations in male populations). Full lines indicate the bounds of the 95% confidence interval around the regression line. Dots indicate the included validation studies.
Figure 4. Results from random-effects meta-regression models for the Framingham Risk Score (validations in male populations). Full lines indicate the bounds of the 95% confidence interval around the regression line. Dots indicate the included validation studies.CC BY-NC · PubMed Central

Verification

Claims the paper makes

45 Not checked yet · 26 No basis given · 25 Own result · 10 Own interpretation · 1 Supported · 1 Supported so far · 1 Own method

Verify all 72 references — free account
  • It may state two separate claims as one. 39
  • Probably not a substantial claim. 24
57 of 57
  • The authors state this as an assumption.

    D values can be converted to c values by making distributional assumptions about the standard deviation of the prognostic index.

    “It is also possible to convert D values to c values by making distributional assumptions with respect to the standard deviation of the prognostic index.26”
  • The authors state this as an assumption.

    Observed and expected event counts for different follow-up times can be extrapolated by assuming a Poisson distribution.

    “an alternative strategy that does not discard information is to apply extrapolation by assuming a Poisson distribution (Supporting Information 3.2).”
  • The authors state this as an assumption.

    Study-specific performance estimates are approximately normally distributed on the logit or log scale.

    “The logit transformation is applied to improve the validity of the Normality assumption, which is used to model variability around the summary c-statistic.30”
  • The authors state this as an assumption.

    In random effects meta-analysis, variation in predictive performance across studies may arise from chance and between-study heterogeneity.

    “In random effects meta-analysis models, it is assumed that variation in predictive performance measures across studies may not only appear due to chance, but is also prone to the (potential) presence of between-study heterogeneity.”
  • The paper relies on this without support.

    Validations of a specific model and existing evidence or data on predictive performance measures are often sparse.

    “validations of a specific model and thus existing evidence or data on predictive performance measures are often sparse.”
  • The authors state this as an assumption.

    Prior independence of μ and τ holds.

    “we assume prior independence of μ and τ.51”
  • The authors state this as an assumption.

    Covariate effects γ are (roughly) linear on the meta-analysis scale.

    “it assumes that covariate effects γ are (roughly) linear on the meta-analysis scale.”
7 of 7

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Citations

Cites

Show all 66 references

Research works printed but not linked: 5

  1. Damen JAAG, 2016, BMJ, 353
  2. Damen JAAG, 2018, PLOS ONE
  3. Snell KI, 2017, Stat Meth Med Res, 096228021770567
  4. Dorfman R, 1938, Biometric Bull, 1, 129
  5. Plummer M. JAGS: A program for analysis of Bayesian graphical models using Gibbs sampling. In: Proceedings of the 3rd international workshop on distributed statistical computing , Vienna, Austria, March 2003.

Cited by

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Metadata

Authors
Debray, T. P., Damen, J. A., Riley, R. D., Snell, K., Reitsma, J. B., Hooft, L., Collins, G. S., & Moons, K. G.
Affiliations
  • University Medical Center Utrecht (NL)
  • Keele University (GB)
  • Centre for Statistics in Medicine, University of Oxford, Oxford, UK
Corresponding author
Debray, Thomas PA
Venue
Statistical Methods in Medical Research
Published
2018-07-23
Volume
28
Issue
9
Pages
2768-2786
ISSN
  • 0962-2802 (ISSN-L)
  • 1477-0334
OpenAlex
W2883189216
Cited by
278
References
66
Citations by year
2026: 55 · 2025: 53 · 2024: 46 · 2023: 46 · 2022: 33 · 2021: 22 · 2020: 13 · 2019: 7 · 2018: 1
FWCI
2.12
Type
journal article
Language
en
Open access
Locations
  • Statistical Methods in Medical Research (publishedVersion, cc-by-nc)
  • PubMed Central (publishedVersion, cc-by-nc)
  • PubMed (publishedVersion)
  • Keele Research Repository (Keele University) (submittedVersion, cc-by)
  • Utrecht University Repository (Utrecht University) (submittedVersion, other-oa)
  • University of Birmingham Research Portal (University of Birmingham) (submittedVersion)
Funders
  • Netherlands Organization for Scientific Research (91617050)
  • Cochrane Methods Innovation Funds Round 2 (MTH001F)
Topics
  • Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Meta-analysis and systematic reviews
  • Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Epidemiology
  • Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Clinical Trials
Keywords
prediction model validation, binary outcomes, time-to-event outcomes, concordance index, calibration slope, observed-to-expected ratio, study heterogeneity, Bayesian meta-analysis, prior distributions, EuroSCORE II, Framingham risk score
MeSH terms
Systematic Reviews as Topic, Bayes Theorem, Calibration, Humans, Prognosis, Research Design, Meta-Analysis as Topic, Models, Statistical, Risk Assessment

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