Marcus Müllner, MD; Hugh Matthews, BSc, MBBS; Douglas G. Altman, DSc
Acknowledgments: The authors thank the BMJ staff, particularly Richard Smith, for providing the environment that enabled this research project.
Requests for Single Reprints: Marcus Müllner, MD, Universitätsklinik für Notfallmedizin, Allgemeines Krankenhaus Wien, Währinger Gürtel 18-20/6D, A-1090 Vienna, Austria; e-mail, firstname.lastname@example.org.
Current Author Addresses: Dr. Müllner: Universitätsklinik für Notfallmedizin, Allgemeines Krankenhaus Wien, Währinger Gürtel 18-20/6D, A-1090 Vienna, Austria.
Mr. Matthews: Sandbanks, Graveney, Faversham, Kent ME13 9DJ, United Kingdom.
Dr. Altman: ICRF Medical Statistics Group, Centre for Statistics in Medicine, Institute of Health Sciences, Old Road, Headington, Oxford OX3 7LF, United Kingdom.
Author Contributions: Conception and design: M. Müllner, H. Matthews, D.G. Altman.
Analysis and interpretation of the data: M. Müllner, D.G. Altman.
Drafting of the article: M. Müllner, H. Matthews, D.G. Altman.
Critical revision of the article for important intellectual content: M. Müllner, H. Matthews, D.G. Altman.
Final approval of the article: M. Müllner, H. Matthews, D.G. Altman.
Statistical expertise: M. Müllner, D.G. Altman.
Administrative, technical, or logistic support: M. Müllner.
Collection and assembly of data: M. Müllner, H. Matthews.
The use of complex statistical models to adjust for confounding is common in medical research.
To determine the frequency and adequacy of adjustment for confounding in medical articles.
34 scientific medical journals with a high impact factor.
Frequency of reporting on methods used to adjust for confounding in 537 original research articles published in January 1998.
Of the 537 articles, 169 specified that adjustment for confounding was used. In 1 paper in 10, it was unclear which statistical method was used or for which variables adjustment was made. In 45% of papers, it was not clear how multicategory or continuous variables were treated in the analysis. Inadequate reporting was less frequent if an author was affiliated with a department of statistics, epidemiology, or public health and if articles were published in journals with a high impact factor.
Details of methods used to adjust for confounding are frequently not reported in original research articles.
Müllner M, Matthews H, Altman DG. Reporting on Statistical Methods To Adjust for Confounding: A Cross-Sectional Survey. Ann Intern Med. 2002;136:122–126. doi: 10.7326/0003-4819-136-2-200201150-00009
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Published: Ann Intern Med. 2002;136(2):122-126.
Cardiology, Coronary Risk Factors, Neurology, Prevention/Screening, Pulmonary/Critical Care.
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