American College of Physicians: Internal Medicine — Doctors for Adults ®

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Thursday, August 14, 2008

Genomics making warfarin easier to manage

Warfarin is a very challenging drug to prescribe and manage. Not only is the therapeutic window narrow, but achieving the correct dose and maintaining a stable international normalized ratio (INR) for patients can be problematic. Any reasonably cost- and time-effective improvement in warfarin management would be welcomed by most clinicians.

Over the last several years new genetic tests for variants in the CYP2C9 and VKORC1 genes have been developed that predict a substantial component of warfarin metabolism. Many scientists and academic health care providers feel that prospective use of these tests may save lives and health care resources. To date, several small studies comparing the use of genetic testing to standard of care have produced mixed results. There may be evidence for reduced use of blood draws for INRs and office visits, but no large trial has demonstrated a mortality benefit. The FDA has altered warfarin's labeling to reflect this new information.

A number of companies and health care systems already have geared up to offer warfarin pharmacogenetic tests with a rapid turn-around time. The National Heart, Lung and Blood Institute of the National Institutes of Health started a major trial of warfarin pharmacogenetic testing through the University of Pennsylvania, which should greatly enhance our understanding of the clinical utility of such tests.

Interestingly, the Centers for Medicare and Medicaid Services opened a National Coverage Analysis (NCA) of the topic. The public comment for this NCA runs until Sept. 3. For some in the personalized medicine community, this NCA is viewed as a critical test case of personalized medicine predicated on genomic information. Perhaps this overstates the situation. It probably is best viewed as an opportunity for a much-needed dialogue between supporters of personalized medicine and evidence-based medicine.

Will the nation's largest health care payer accept the current evidence supporting the use of warfarin pharmacogenetic testing in routine care? A recent review using the Rapid ACCE format by McClain et al. raised serious concerns regarding gaps in the current evidence base. However, this is a rapidly moving field and more data are now available.

In a time of rapid advances in genetics and genomics and spiraling health care costs, any significant "evidentiary gap" will be increasingly problematic for promising and potentially very significant improvements in standard of care. Substantial resources should be directed at re-tooling our research and health care delivery systems to rapidly and responsibly generate the types of effectiveness data needed to separate the wheat from the chaff in genomics, and more broadly, all emerging health care technologies.

W. Gregory Feero, MD, PhD, a family physician with a doctorate in human genetics, is senior adviser for genomic medicine in the Office of the Director at the NIH's National Human Genome Research Institute. His column runs every issue in ACP Internist

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2 Comments:

Anonymous Anonymous said...

Thanks for writing this post. You made all the right connections that I didn't see until now.

August 15, 2008 at 11:17 AM  
Anonymous Anonymous said...

I think we are missing the bus on warfarin testing.

I am a practicing hematologist. I cannot fathom what the benefit of warfarin genetic testing is supposed to be.

I am a proponent of genetic testing. I believe that BRCA testing saves lives, and I send a lot of tests. I have lectured to community groups about the importance of BRCA testing.

I think there's a huge difference between that and warfarin testing. We already have a well-established clinical platform for dosing and adjusting warfarin dosing: INR testing. INR tests are rapid, cheap, and are well-correlated to bleeding risk.

We already know that we have to follow some patients more carefully on warfarin; that fact becomes clinically evident in short order. Labile INRs in my office are followed with shorter intervals of testing, and that would be true regardless of the result of genetic testing. So I fail to see the added value of testing.

I would like to see a study where patients were managed differently according to warfarin genetic testing, and that the outcomes were improved. So far, there hasn't been such a paper.

Finally, in the specific case of warfarin, we are expecting the approval of two if not three new oral anticoagulants that will not require any INR testing at all. Warfarin genetic testing is solving a clinical problem that may not exist in a few years.

I would prefer we devote our precious health research resources to creating tests that actually benefit doctors and patients, not just ones that enrich the testing companies.

InteractMD.com

August 22, 2008 at 12:02 PM  

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Blog log

Members of the American College of Physicians contribute posts from their own sites to ACP Internistand ACP Hospitalist. Contributors include:

Albert Fuchs, MD
Albert Fuchs, MD, FACP, graduated from the University of California, Los Angeles School of Medicine, where he also did his internal medicine training. Certified by the American Board of Internal Medicine, Dr. Fuchs spent three years as a full-time faculty member at UCLA School of Medicine before opening his private practice in Beverly Hills in 2000.

And Thus, It Begins
Amanda Xi, ACP Medical Student Member, is a first-year medical student at the OUWB School of Medicine, charter class of 2015, in Rochester, Mich., from which she which chronicles her journey through medical training from day 1 of medical school.

Auscultation
Ira S. Nash, MD, FACP, is the senior vice president and executive director of the North Shore-LIJ Medical Group, and a professor of Cardiology and Population Health at Hofstra North Shore-LIJ School of Medicine. He is Board Certified in Internal Medicine and Cardiovascular Diseases and was in the private practice of cardiology before joining the full-time faculty of Massachusetts General Hospital.

Zackary Berger
Zackary Berger, MD, ACP Member, is a primary care doctor and general internist in the Division of General Internal Medicine at Johns Hopkins. His research interests include doctor-patient communication, bioethics, and systematic reviews.

Controversies in Hospital Infection Prevention
Run by three ACP Fellows, this blog ponders vexing issues in infection prevention and control, inside and outside the hospital. Daniel J Diekema, MD, FACP, practices infectious diseases, clinical microbiology, and hospital epidemiology in Iowa City, Iowa, splitting time between seeing patients with infectious diseases, diagnosing infections in the microbiology laboratory, and trying to prevent infections in the hospital. Michael B. Edmond, MD, FACP, is a hospital epidemiologist in Richmond, Va., with a focus on understanding why infections occur in the hospital and ways to prevent these infections, and sees patients in the inpatient and outpatient settings. Eli N. Perencevich, MD, ACP Member, is an infectious disease physician and epidemiologist in Iowa City, Iowa, who studies methods to halt the spread of resistant bacteria in our hospitals (including novel ways to get everyone to wash their hands).

db's Medical Rants
Robert M. Centor, MD, FACP, contributes short essays contemplating medicine and the health care system.

Suneel Dhand, MD, ACP Member
Suneel Dhand, MD, ACP Member, is a practicing physician in Massachusetts. He has published numerous articles in clinical medicine, covering a wide range of specialty areas including; pulmonology, cardiology, endocrinology, hematology, and infectious disease. He has also authored chapters in the prestigious "5-Minute Clinical Consult" medical textbook. His other clinical interests include quality improvement, hospital safety, hospital utilization, and the use of technology in health care.

DrDialogue
Juliet K. Mavromatis, MD, FACP, provides a conversation about health topics for patients and health professionals.

Dr. Mintz' Blog
Matthew Mintz, MD, FACP, has practiced internal medicine for more than a decade and is an Associate Professor of Medicine at an academic medical center on the East Coast. His time is split between teaching medical students and residents, and caring for patients.

Everything Health
Toni Brayer, MD, FACP, blogs about the rapid changes in science, medicine, health and healing in the 21st century.

FutureDocs
Vineet Arora, MD, FACP, is Associate Program Director for the Internal Medicine Residency and Assistant Dean of Scholarship & Discovery at the Pritzker School of Medicine for the University of Chicago. Her education and research focus is on resident duty hours, patient handoffs, medical professionalism, and quality of hospital care. She is also an academic hospitalist.

Glass Hospital
John H. Schumann, MD, FACP, provides transparency on the workings of medical practice and the complexities of hospital care, illuminates the emotional and cognitive aspects of caregiving and decision-making from the perspective of an active primary care physician, and offers behind-the-scenes portraits of hospital sanctums and the people who inhabit them.

Gut Check
Ryan Madanick, MD, ACP Member, is a gastroenterologist at the University of North Carolina School of Medicine, and the Program Director for the GI & Hepatology Fellowship Program. He specializes in diseases of the esophagus, with a strong interest in the diagnosis and treatment of patients who have difficult-to-manage esophageal problems such as refractory GERD, heartburn, and chest pain.

I'm dok
Mike Aref, MD, PhD, FACP, is an academic hospitalist with an interest in basic and clinical science and education, with interests in noninvasive monitoring and diagnostic testing using novel bedside imaging modalities, diagnostic reasoning, medical informatics, new medical education modalities, pre-code/code management, palliative care, patient-physician communication, quality improvement, and quantitative biomedical imaging.

Informatics Professor
William Hersh, MD, FACP, Professor and Chair, Department of Medical Informatics & Clinical Epidemiology, Oregon Health & Science University, posts his thoughts on various topics related to biomedical and health informatics.

David Katz, MD
David L. Katz, MD, MPH, FACP, is an internationally renowned authority on nutrition, weight management, and the prevention of chronic disease, and an internationally recognized leader in integrative medicine and patient-centered care.

Just Oncology
Richard Just, MD, ACP Member, has 36 years in clinical practice of hematology and medical oncology. His blog is a joint publication with Gregg Masters, MPH.

KevinMD
Kevin Pho, MD, ACP Member, offers one of the Web's definitive sites for influential health commentary.

MD Whistleblower
Michael Kirsch, MD, FACP, addresses the joys and challenges of medical practice, including controversies in the doctor-patient relationship, medical ethics and measuring medical quality. When he's not writing, he's performing colonoscopies.

Medical Lessons
Elaine Schattner, MD, FACP, shares her ideas on education, ethics in medicine, health care news and culture. Her views on medicine are informed by her past experiences in caring for patients, as a researcher in cancer immunology, and as a patient who's had breast cancer.

Mired in MedEd
Alexander M. Djuricich, MD, FACP, is the Associate Dean for Continuing Medical Education (CME), and a Program Director in Medicine-Pediatrics at the Indiana University School of Medicine in Indianapolis, where he blogs about medical education.

More Musings
Rob Lamberts, MD, ACP Member, a med-peds and general practice internist, returns with "volume 2" of his personal musings about medicine, life, armadillos and Sasquatch at More Musings (of a Distractible Kind).

Prescriptions
David M. Sack, MD, FACP, practices general gastroenterology at a small community hospital in Connecticut. His blog is a series of musings on medicine, medical care, the health care system and medical ethics, in no particular order.

Reflections of a Grady Doctor
Kimberly Manning, MD, FACP, reflects on the personal side of being a doctor in a community hospital in Atlanta.

The Blog of Paul Sufka
Paul Sufka, MD, ACP Member, is a board certified rheumatologist in St. Paul, Minn. He was a chief resident in internal medicine with the University of Minnesota and then completed his fellowship training in rheumatology in June 2011 at the University of Minnesota Department of Rheumatology. His interests include the use of technology in medicine.

Technology in (Medical) Education
Neil Mehta, MBBS, MS, FACP, is interested in use of technology in education, social media and networking, practice management and evidence-based medicine tools, personal information and knowledge management.

Peter A. Lipson, MD
Peter A. Lipson, MD, ACP Member, is a practicing internist and teaching physician in Southeast Michigan. The blog, which has been around in various forms since 2007, offers musings on the intersection of science, medicine, and culture.

Why is American Health Care So Expensive?
Janice Boughton, MD, FACP, practiced internal medicine for 20 years before adopting a career in hospital and primary care medicine as a locum tenens physician. She lives in Idaho when not traveling.

World's Best Site
Daniel Ginsberg, MD, FACP, is an internal medicine physician who has avidly applied computers to medicine since 1986, when he first wrote medically oriented computer programs. He is in practice in Tacoma, Washington.

Other blogs of note:

American Journal of Medicine
Also known as the Green Journal, the American Journal of Medicine publishes original clinical articles of interest to physicians in internal medicine and its subspecialities, both in academia and community-based practice.

Clinical Correlations
A collaborative medical blog started by Neil Shapiro, MD, ACP Member, associate program director at New York University Medical Center's internal medicine residency program. Faculty, residents and students contribute case studies, mystery quizzes, news, commentary and more.

Interact MD
Michael Benjamin, MD, ACP member, doesn't accept industry money so he can create an independent, clinician-reviewed space on the Internet for physicians to report and comment on the medical news of the day.

PLoS Blog
The Public Library of Science's open access materials include a blog.

White Coat Rants
One of the most popular anonymous blogs written by an emergency room physician.

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