Featured Research

from universities, journals, and other organizations

Experimental Methods: No Adjustment Method Fully Resolves Confounding By Indication

Date:
May 26, 2009
Source:
Boston University Medical Center
Summary:
Researchers have found that no adjustment method fully resolves confounding by indication in observational studies, meaning when the validity of a study is threatened by unmeasured confounding, it is not straightforward to determine which method of adjustment, if any, is most effective in obtaining a valid and precise estimate of effect.

Researchers at Boston University School of Medicine (BUSM) and Boston University School of Public Health have found that no adjustment method fully resolves confounding by indication in observational studies, meaning when the validity of a study is threatened by unmeasured confounding, it is not straightforward to determine which method of adjustment, if any, is most effective in obtaining a valid and precise estimate of effect.

The study appears online in the Journal of Clinical Epidemiology.

According to researchers, conventional methods to adjust for confounding, such as restriction and multivariable regression, leave residual confounding because of unmeasured factors. Propensity scores (PS) and instrumental variable (IV) methods have become increasingly popular with the intent to address residual confounding by simulating a randomized environment.

Using data from the Breast Cancer Effectiveness in Older Women study, a collaboration of investigators from the National Cancer Institute-funded Cancer Research Network, the researchers compared methods used to reduce confounding to estimate incidence rates of breast cancer recurrence in older women who received adjuvant chemotherapy compared with women who did not.

The researchers examined women 65 years of age or older diagnosed with early stage breast cancer. For women classified as high risk for recurrence, 20 percent experienced a breast cancer recurrence. In the unrestricted cohort, receipt of adjuvant chemotherapy was associated with recurrence. The PS distributions among women who received chemotherapy among those who did not showed no substantial overlap. Using the IV method, recurrence yielded a protective estimate. However, imbalances of measured factors across levels of the IV suggested residual confounding.

"With minimal trial-based information available to inform clinical guidelines, which currently offer no guidance for treating older women with cancer, non-randomized studies are vitally important," said lead author Jaclyn Bosco, MPH, project director in the Section of Geriatrics at BUSM. "Non-randomized studies are only reliable when confounding by indication is handled adequately. When treatment with adjuvant chemotherapy among older patients is based on clinical judgment, controlling for prognostic factors alone leaves residual confounding by indication."

Researchers further stated that PS and IV analysis methods can be useful under specific situations, but neither method adequately controlled confounding by indication in this study.

This study was funded by the National Cancer Institute, National Institutes of Health, and the Department of Health and Human Services. These organizations had no role in the design and conduct of the study, the collection, management, analysis and interpretation of the data, or the preparation, review and approval of the manuscript.


Story Source:

The above story is based on materials provided by Boston University Medical Center. Note: Materials may be edited for content and length.


Cite This Page:

Boston University Medical Center. "Experimental Methods: No Adjustment Method Fully Resolves Confounding By Indication." ScienceDaily. ScienceDaily, 26 May 2009. <www.sciencedaily.com/releases/2009/05/090526140740.htm>.
Boston University Medical Center. (2009, May 26). Experimental Methods: No Adjustment Method Fully Resolves Confounding By Indication. ScienceDaily. Retrieved August 2, 2014 from www.sciencedaily.com/releases/2009/05/090526140740.htm
Boston University Medical Center. "Experimental Methods: No Adjustment Method Fully Resolves Confounding By Indication." ScienceDaily. www.sciencedaily.com/releases/2009/05/090526140740.htm (accessed August 2, 2014).

Share This




More Health & Medicine News

Saturday, August 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Texas Quintuplets Head Home

Texas Quintuplets Head Home

Reuters - US Online Video (Aug. 1, 2014) After four months in the hospital, the first quintuplets to be born at Baylor University Medical Center head home. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Ebola Patient Coming to U.S. for Treatment

Ebola Patient Coming to U.S. for Treatment

Reuters - US Online Video (Aug. 1, 2014) A U.S. aid worker infected with Ebola while working in West Africa will be treated in a high security ward at Emory University in Atlanta. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Ebola Vaccine Might Be Coming, But Where's It Been?

Ebola Vaccine Might Be Coming, But Where's It Been?

Newsy (Aug. 1, 2014) Health officials are working to fast-track a vaccine — the West-African Ebola outbreak has killed more than 700. But why didn't we already have one? Video provided by Newsy
Powered by NewsLook.com
Study Links Certain Birth Control Pills To Breast Cancer

Study Links Certain Birth Control Pills To Breast Cancer

Newsy (Aug. 1, 2014) Previous studies have made the link between birth control and breast cancer, but the latest makes the link to high-estrogen oral contraceptives. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins