This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Stanley, K. Search for Related Content PubMed PubMed Citation Articles by Stanley, K. Related Collections Clinical Studies

(Circulation. 2007;115:1164-1169.)
© 2007 American Heart Association, Inc.

Statistical Primer for Cardiovascular Research

Design of Randomized Controlled Trials

Kenneth Stanley, PhD

From the Department of Biostatistics, Harvard School of Public Health, Boston, Mass.

Correspondence to Kenneth Stanley, PhD, Department of Biostatistics, Harvard School of Public Health, 651 Huntington Ave, Boston, MA 02115. E-mail kstanley@sdac.harvard.edu

Key Words: randomized controlled trials • statistics • trials

An extract of the first 250 words of the full text is provided, because this article has no abstract.

	Introduction

 
A major factor in the rapid advance of medical science over the past 50 years has been the development and refinement of the clinical research method known as the randomized controlled trial (RCT). A clinical trial is defined as a prospective scientific experiment that involves human subjects in whom treatment is initiated for the evaluation of a therapeutic intervention. In an RCT, each patient is assigned to receive a specific treatment intervention by a chance mechanism.

Nothing more clearly indicates the key role of an RCT in modern clinical research than the placement of this specific research method at the top of the list of levels of evidence in evidence-based medicine.¹ According to this classification, significant results of an RCT are more definitive than any other type of clinical research information.

The purpose of this article is to present an overview of the design of RCTs. Some of the principles of a high-quality study, such as the use of randomization, placebos, and double-blind designs are well known. Other principles such as stratification, use of a decision-making structure, and statistical power are known by many investigators but are not universally recognized or fully understood. These features plus others that indicate the design of a high-quality RCT are discussed. A companion article on the conduct and evaluation of RCTs will appear in a future issue of this journal.

	Clarity of Study Objective

 
One of the most easily recognized aspects of a well-designed and conducted clinical trial is the apparent clarity of the research mechanism evident in . . . [Full Text of this Article]

This article has been cited by other articles:

				F. Zannad, P. Bousquet, and L. Monassier CHAPTER 11 Clinical Pharmacology of Cardiovascular Drugs ESC Textbook of Cardiovascular Medicine, January 1, 2009; 2(1): med-9780199566990-chapter - med-9780199566990-chapter. [Abstract] [Full Text] [PDF]

				B. K. Nallamothu, R. A. Hayward, and E. R. Bates Beyond the Randomized Clinical Trial: The Role of Effectiveness Studies in Evaluating Cardiovascular Therapies Circulation, September 16, 2008; 118(12): 1294 - 1303. [Full Text] [PDF]

				M. G. Larson Analysis of Variance Circulation, January 1, 2008; 117(1): 115 - 121. [Full Text] [PDF]

				B. R. Overholser and K. M. Sowinski Biostatistics Primer: Part I Nutr Clin Pract, December 1, 2007; 22(6): 629 - 635. [Abstract] [Full Text] [PDF]