0
Summaries for Patients |

Reporting on Statistical Methods To Adjust for Confounding FREE

[+] Article and Author Information

The summary below is from the full report titled “Reporting on Statistical Methods To Adjust for Confounding: A Cross-Sectional Survey.” It is in the 15 January 2002 issue of Annals of Internal Medicine (volume 136, pages 122-126). The authors are M Müllner, H Matthews, and DG Altman.


Ann Intern Med. 2002;136(2):I47. doi:10.7326/0003-4819-136-2-200201150-00004
Text Size: A A A

What is the problem and what is known about it so far?

Research projects often try to show that a condition (such as age) has a strong association with a health care outcome (such as death from heart disease). Confounding occurs when the health care outcome is influenced by factors other than the one that a researcher thinks is the most important. These factors are called confounders. For example, suppose that a researcher was studying whether pregnant women who drink coffee are more likely to have small babies than are women who do not drink coffee. Now suppose that the researcher found that the babies of coffee drinkers weighed less than the babies of women who did not drink coffee. However, the researcher failed to consider the possibility that women who drink a lot of coffee are also more likely to drink alcohol and use tobacco. In this case, alcohol and tobacco are potential confounders. In fact, drinking alcohol and smoking can lead to babies who weigh less at birth. If these behaviors are more common in coffee drinkers than in non–coffee drinkers, researchers say that these factors may “confound” the relationship between coffee drinking and birth weight. An analysis that uses special statistical methods to account for potential confounders might conclude that coffee drinking itself does not result in low birth weight. Adjustment for confounding is very important because it can prevent people from drawing incorrect conclusions about what information is important in patient care.

Why did the researchers do this particular study?

To determine how frequently researchers describe how they adjusted for confounders in their analysis.

Who was studied?

The researchers studied 537 original research articles published in 34 medical journals in January 1998.

How was the study done?

The researchers examined each article and collected information about whether and how it reported the methods that the original researchers used to adjust for confounding.

What did the researchers find?

Of the 537 articles examined, 169 stated that the researchers adjusted for confounding. Many of the 169 articles that adjusted for confounding provided too little information to decide whether the researchers had done so correctly. Articles that had an author affiliated with a department of statistics, epidemiology, or public health were much more likely to provide a full description of their adjustment for confounding.

What were the limitations of the study?

The study included only articles from a single month in one year and sampled only 34 journals.

What are the implications of the study?

Researchers frequently do not publish enough detail about the methods they use to adjust for confounders. Researchers should provide adequate information about confounding, and journal editors should insist that they do.

Figures

Tables

References

Letters

NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Comments

Submit a Comment
Submit a Comment

Summary for Patients

Clinical Slide Sets

Terms of Use

The In the Clinic® slide sets are owned and copyrighted by the American College of Physicians (ACP). All text, graphics, trademarks, and other intellectual property incorporated into the slide sets remain the sole and exclusive property of the ACP. The slide sets may be used only by the person who downloads or purchases them and only for the purpose of presenting them during not-for-profit educational activities. Users may incorporate the entire slide set or selected individual slides into their own teaching presentations but may not alter the content of the slides in any way or remove the ACP copyright notice. Users may make print copies for use as hand-outs for the audience the user is personally addressing but may not otherwise reproduce or distribute the slides by any means or media, including but not limited to sending them as e-mail attachments, posting them on Internet or Intranet sites, publishing them in meeting proceedings, or making them available for sale or distribution in any unauthorized form, without the express written permission of the ACP. Unauthorized use of the In the Clinic slide sets will constitute copyright infringement.

Toolkit

Want to Subscribe?

Learn more about subscription options

Advertisement
Related Articles
Related Point of Care
Topic Collections
PubMed Articles
Forgot your password?
Enter your username and email address. We'll send you a reminder to the email address on record.
(Required)
(Required)