This Article  • Full text  • PDF  • Send to a friend  • Save in My Folder  • Save to citation manager  • Permissions  Citing Articles  • Citation map  • Contact me when this article is cited  Related Content  • Similar articles in this journal  Topic Collections  • Cardiovascular System  • Statistics and Research Methods  • Cardiovascular Disease/ Myocardial Infarction  • Drug Therapy  • Drug Therapy, Other  • Alert me on articles by topic  Social Bookmarking   What's this?

Rolf H. H. Groenwold, MD, PhD; A. Rogier T. Donders, PhD; Geert J. M. G. van der Heijden, PhD; Arno W. Hoes, MD, PhD; Maroeska M. Rovers, PhD

Arch Intern Med. 2009;169(16):1532-1534.

	Since this article does not have an abstract, we have provided the first 150 words of the full text and any section headings.

Randomized controlled trials (RCTs) are considered the paradigm to study effects of medical interventions because randomization (theoretically) results in comparability of study groups.^1-2 Confounding is therefore considered a nonissue in RCTs. Nevertheless, effects that are estimated within subgroups of RCTs can be confounded. This argument might seem rather obvious because the issue is just elementary epidemiology, but it has not received adequate attention (ie, minimal or no discussion on this issue is found in various standard texts on clinical trials). Confounding of subgroup effects has mainly been described in relation to individual patient data (IPD) meta-analyses.^3-4 However, proposed methods to control for such confounding (ie, the so-called 2-stage approach) fail, as illustrated by the example described herein, which exemplifies confounding of subgroup . . . [Full Text of this Article]

AUTHOR INFORMATION


CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter     What's this?