0
We're unable to sign you in at this time. Please try again in a few minutes.
Retry
We were able to sign you in, but your subscription(s) could not be found. Please try again in a few minutes.
Retry
There may be a problem with your account. Please contact the AMA Service Center to resolve this issue.
Contact the AMA Service Center:
Telephone: 1 (800) 262-2350 or 1 (312) 670-7827  *   Email: subscriptions@jamanetwork.com
Error Message ......
Viewpoint |

The Potential for Postrandomization Confounding in Randomized Clinical Trials

JoAnn E. Manson, MD, DrPH1; Chrisandra L. Shufelt, MD2; James M. Robins, MD3
[+] Author Affiliations
1Division of Preventive Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
2Barbra Streisand Women’s Heart Center, Cedars-Sinai Heart Institute, Los Angeles, California
3Departments of Biostatistics and Epidemiology, Harvard T. H. Chan School of Public Health, Boston, Massachusetts
JAMA. 2016;315(21):2273-2274. doi:10.1001/jama.2016.3676.
Text Size: A A A
Published online

Extract

In this Viewpoint, JoAnn Manson and colleagues discuss the risk of postrandomization “confounding,” a bias that can be introduced in long-duration trials of sustained interventions, using statin initiation after randomization in Women’s Health Initiative trials as an example.

Randomized clinical trials (RCTs) are considered the “gold standard” for evaluating an intervention’s efficacy and safety.1 Although large-scale RCTs are nearly always free of baseline confounding because randomization balances the distribution of measured and unmeasured risk factors across treatment groups, biases may emerge after randomization because of differential use of nonstudy medication or treatments, imbalanced rates of disease screening, differential loss to follow-up, and other differences between treatment groups. Such postrandomization “confounding” is more likely to occur in long-term trials or pragmatic trials taking place in typical patient care settings. Because community-based long-duration pragmatic trials are increasingly being used to evaluate sustained interventions, it is important for researchers to use available methodological approaches to assess the presence of such biases1 and for clinicians to be aware of potential sources of confounding when interpreting results of RCTs.

Figures in this Article

Sign in

Purchase Options

• Buy this article
• Subscribe to the journal
• Rent this article ?

First Page Preview

View Large
First page PDF preview

Figures

Place holder to copy figure label and caption
Figure.
Statin Use in the Women’s Health Initiative Hormone Therapy Trials, According to Treatment Group in Each Trial

Mean percentage of statin users at each annual visit by randomization group. Error bars indicate 95% CI; CEE, conjugated equine estrogens; MPA, medroxyprogesterone acetate.

Graphic Jump Location

Tables

References

CME
Also Meets CME requirements for:
Browse CME for all U.S. States
Accreditation Information
The American Medical Association is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The AMA designates this journal-based CME activity for a maximum of 1 AMA PRA Category 1 CreditTM per course. Physicians should claim only the credit commensurate with the extent of their participation in the activity. Physicians who complete the CME course and score at least 80% correct on the quiz are eligible for AMA PRA Category 1 CreditTM.
Note: You must get at least of the answers correct to pass this quiz.
Please click the checkbox indicating that you have read the full article in order to submit your answers.
Your answers have been saved for later.
You have not filled in all the answers to complete this quiz
The following questions were not answered:
Sorry, you have unsuccessfully completed this CME quiz with a score of
The following questions were not answered correctly:
Commitment to Change (optional):
Indicate what change(s) you will implement in your practice, if any, based on this CME course.
Your quiz results:
The filled radio buttons indicate your responses. The preferred responses are highlighted
For CME Course: A Proposed Model for Initial Assessment and Management of Acute Heart Failure Syndromes
Indicate what changes(s) you will implement in your practice, if any, based on this CME course.

Multimedia

Some tools below are only available to our subscribers or users with an online account.

3,527 Views
0 Citations
×

Sign in

Purchase Options

• Buy this article
• Subscribe to the journal
• Rent this article ?

Related Content

Customize your page view by dragging & repositioning the boxes below.

Articles Related By Topic
Related Collections
PubMed Articles
Jobs
JAMAevidence.com

Users' Guides to the Medical Literature: A Manual for Evidence-Based Clinical Practice, 3rd ed
The Biological Agent

Users' Guides to the Medical Literature: A Manual for Evidence-Based Clinical Practice, 3rd ed
Is There Potentially Compelling Evidence for a Class Effect?

brightcove.createExperiences();