Spurious precision? Meta-analysis of observational studies.
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TLDR
A Medline search identified 566 articles published in 1995 and indexed with the medical subject heading (MeSH) term “meta-analysis” and randomly selected 100 articles, finding about half were based on observational studies, mainly cohort and case-control studies of medical interventions or aetiological associations.Abstract:
In previous articles we have focused on the potentials, principles, and pitfalls of meta-analysis of randomised controlled trials.1 2 3 4 5 Meta-analysis of observational data is, however, also becoming common. In a Medline search we identified 566 articles (excluding those published as letters) published in 1995 and indexed with the medical subject heading (MeSH) term “meta-analysis.” We randomly selected 100 of these articles and examined them further. Sixty articles reported on actual meta-analyses, and 40 were methodological papers, editorials, and traditional reviews (1). Among the meta-analyses, about half were based on observational studies, mainly cohort and case-control studies of medical interventions or aetiological associations.
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Characteristics of 100 articles randomly selected from articles published in 1995 and indexed in Medline with keyword “meta-analysis”
The randomised controlled trial is the principal research design in the evaluation of medical interventions. However, aetiological hypotheses—for example, those relating common exposures to the occurrence of disease—cannot generally be tested in randomised experiments. Does breathing other people's tobacco smoke cause lung cancer, drinking coffee cause coronary heart disease, and eating a diet rich in saturated fat cause breast cancer? Studies of such “menaces of daily life”6 use observational designs or examine the presumed biological mechanisms in the laboratory. In these situations the risks involved are generally small, but once a large proportion of the population is exposed, the potential public health implications of these associations—if they are causal—can be striking.
Analyses of observational data also have a role in medical effectiveness research.7 The evidence available from clinical trials will rarely answer all the important questions. Most trials are conducted to establish efficacy and safety of a single agent in a specific clinical situation. Owing to the limited size of such trials, less common adverse effects of drugs may only be detected in case-control …read more
Citations
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Journal ArticleDOI
The Strengthening the Reporting of Observational Studies in Epidemiology [STROBE] statement: guidelines for reporting observational studies
Erik von Elm,Douglas G. Altman,Matthias Egger,Matthias Egger,Stuart J. Pocock,Peter C Gøtzsche,Jan P. Vandenbroucke +6 more
TL;DR: The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) initiative developed recommendations on what should be included in an accurate and complete report of an observational study, resulting in a checklist of 22 items (the STROBE statement) that relate to the title, abstract, introduction, methods, results, and discussion sections of articles.
Journal ArticleDOI
The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies
E von Elm,Douglas G. Altman,Matthias Egger,Matthias Egger,Stuart J. Pocock,Peter C Gøtzsche,Jan P. Vandenbroucke +6 more
TL;DR: The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Initiative developed recommendations on what should be included in an accurate and complete report of an observational study, resulting in a checklist of 22 items that relate to the title, abstract, introduction, methods, results, and discussion sections of articles.
Journal ArticleDOI
The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies
Erik von Elm,Douglas G. Altman,Matthias Egger,Matthias Egger,Stuart J. Pocock,Peter C Gøtzsche,Jan P. Vandenbroucke +6 more
TL;DR: The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Initiative developed recommendations on what should be included in an accurate and complete report of an observational study, resulting in a checklist of 22 items that relate to the title, abstract, introduction, methods, results, and discussion sections of articles.
Journal ArticleDOI
The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Statement: Guidelines for Reporting Observational Studies
E von Elm,Douglas G. Altman,Matthias Egger,Matthias Egger,Stuart J. Pocock,Peter C Gøtzsche,Jan P. Vandenbroucke +6 more
TL;DR: The STROBE Statement is a checklist of items that should be addressed in articles reporting on the 3 main study designs of analytical epidemiology: cohort, casecontrol, and cross-sectional studies; these recommendations are not prescriptions for designing or conducting studies.
Journal ArticleDOI
Recommendations for examining and interpreting funnel plot asymmetry in meta-analyses of randomised controlled trials
Jonathan A C Sterne,Alex J. Sutton,John P. A. Ioannidis,Norma Terrin,David R. Jones,Joseph Lau,James R. Carpenter,Gerta Rücker,Roger M. Harbord,Christopher H. Schmid,Jennifer Tetzlaff,Jonathan J Deeks,Jaime Peters,Petra Macaskill,Guido Schwarzer,Sue Duval,Douglas G. Altman,David Moher,Julian P T Higgins +18 more
TL;DR: How to interpret funnel plot asymmetry, recommends appropriate tests, and explains the implications for choice of meta-analysis model are described.
References
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Bias in meta-analysis detected by a simple, graphical test
TL;DR: Funnel plots, plots of the trials' effect estimates against sample size, are skewed and asymmetrical in the presence of publication bias and other biases Funnel plot asymmetry, measured by regression analysis, predicts discordance of results when meta-analyses are compared with single large trials.
Journal ArticleDOI
The environment and disease: association or causation?
TL;DR: The criteria outlined in "The Environment and Disease: Association or Causation?" help identify the causes of many diseases, including cancers of the reproductive system.
Journal Article
The environment and disease: association or causation?
TL;DR: This paper contrasts Bradford Hill’s approach with a currently fashionable framework for reasoning about statistical associations – the Common Task Framework – and suggests why following Bradford Hill, 50+ years on, is still extraordinarily reasonable.
Journal ArticleDOI
Blood pressure, stroke, and coronary heart disease: Part 1, prolonged differences in blood pressure: prospective observational studies corrected for the regression dilution bias
Stephen MacMahon,Richard Peto,J E Cutler,Rory Collins,P D Sorlie,James D. Neaton,Robert D. Abbott,Jon Godwin,Alan R. Dyer,Jeremiah Stamler +9 more
TL;DR: The DBP results suggest that for the large majority of individuals, whether conventionally "hypertensive" or "normotensive", a lower blood pressure should eventually confer a lower risk of vascular disease.
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The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers
O.P. Heinonen,D. Albanes +1 more
TL;DR: No reduction in the incidence of lung cancer among male smokers is found after five to eight years of dietary supplementation with alpha-tocopherol or beta carotene, and this trial raises the possibility that these supplements may actually have harmful as well as beneficial effects.