This Article  • Full text  • PDF  • Send to a friend  • Save in My Folder  • Save to citation manager  • Permissions  Citing Articles  • Citation map  • Citing articles on HighWire  • Citing articles on Web of Science (8)  • Contact me when this article is cited  Related Content  • Related article  • Similar articles in JAMA  Social Bookmarking   What's this?

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

To the Editor: The article by Drs Zhang and Yu¹ addresses a common mistake—using the odds ratio (OR) to estimate relative risk (RR) when the disease being studied is common (>10%).¹ The authors' proposed solution is intriguing; however, it may be an oversimplification.

Logistic regression yields an OR between each variable and the outcome of interest. The formula presented to calculate the RR from the OR appears to be reasonable if there is no effect modification—that is, the RR is similar for all levels of the confounding variables. However, it is possible for the OR to display homogeneity across covariate patterns while the RR does not because they are calculated differently.

More important, the proposed adjustment of the confidence interval (CI) can produce narrower intervals than direct estimates. The proposed correction ignores the variance of P₀; however, P₀ is usually only a sample-based estimate. Directly estimated CIs for RR . . . [Full Text of this Article]

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

RELATED ARTICLE

What's the Relative Risk?: A Method of Correcting the Odds Ratio in Cohort Studies of Common Outcomes
Jun Zhang and Kai F. Yu
JAMA. 1998;280(19):1690-1691.
ABSTRACT | FULL TEXT  

THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES

The Relative Merits of Risk Ratios and Odds Ratios
Cummings
Arch Pediatr Adolesc Med 2009;163:438-445.
ABSTRACT | FULL TEXT  

Estimating the Relative Risk in Cohort Studies and Clinical Trials of Common Outcomes
McNutt et al.
Am J Epidemiol 2003;157:940-943.
ABSTRACT | FULL TEXT  

Reporting Statistical Information in Medical Journal Articles
Cummings and Rivara
Arch Pediatr Adolesc Med 2003;157:321-324.
FULL TEXT  

Logistic Regression Analysis: When the Odds Ratio Does Not Work: An Example Using Intimate Partner Violence Data
McNUTT et al.
J Interpers Violence 2000;15:1050-1059.
ABSTRACT