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Monday, August 12, 2013

Weight loss doesn't decrease strokes and heart attacks in overweight diabetics

Doctors spend a lot of time recommending diet and exercise for weight loss. If you're my patient, unless you're quite fit, you've probably heard me ask you to exercise more and eat less. There is good reason for this. Many short term studies have convinced us of multiple benefits of weight loss, including better sugar control in diabetics, lower blood pressure, improved mood, and higher quality of life.

Nevertheless, there is little data about the long term benefits of weight loss. If you were to design a trial looking to measure the cardiovascular benefits of weight loss you would want to focus on a group of people who would benefit most, a group at high risk for strokes and heart attacks. Overweight diabetics would be a great choice.

Last week the New England Journal of Medicine (NEJM) published the results of a long term trial testing whether intensive lifestyle modification aimed at weight loss would prevent strokes and heart attacks in overweight patients with type 2 diabetes.

Over 5,100 middle aged and elderly patients with type 2 diabetes were enrolled. They were all overweight or obese (BMI 25 or over). They were randomized to two groups. One group was counseled about diet and exercise. They were educated to exercise for about 3 hours per week and consume 1,200 to 1,800 calories daily with less than 30% of the calories from fat. The control group was not given specific targets for calories or exercise. Both groups had their diabetes and other medical problems managed by their own physicians, and their medications were not controlled by the study.

Both groups were followed for an average of 9.6 years to see if one group had fewer strokes, heart attacks, or death due to cardiovascular causes.

Not surprisingly, the lifestyle intervention group lost more weight than the control group. After one year the intervention group lost on average 8.6% of body weight, compared to 0.7% in the control group. After the first year, the intervention group regained some weight, a common occurrence in weight-loss studies (and in the personal experience of dieters). Still, by the end of the study the intervention group lost 6% of their initial body weight, compared to 3.5% in the control group. The intervention group had lower glucose levels (i.e. better diabetes control), was on less medication, and had less serious kidney disease, depression, and sleep apnea.

That's not bad, right? If I had diabetes I would exercise regularly and eat less for those benefits.

So you would think that with all those benefits including the pretty impressive weight loss, the intervention group would have had fewer strokes and heart attacks. They didn't. The numbers of strokes, heart attacks, and deaths in the two groups were not significantly different.

Across the scientific land there was wailing and gnashing of teeth. What happened? Surely, we can't throw in the towel on diet and exercise.

An editorial in the same NEJM issue suggests possible explanations. Perhaps the weight loss achieved in the study was simply too small to decrease cardiovascular risk. That would be a very depressing explanation since the weight loss achieved in the study is greater than most people are able to maintain. Hoping that a larger weight loss is needed for cardiovascular benefits would not be very realistic for real patients. Another possibility is that the cardiovascular benefits only accrue after a longer delay, and that following the patients for longer than 10 years is needed to measure this benefit.

The explanation I find most plausible has to do with the medications the patients were taking. Again, the medications taken by the patients were not controlled by the study; they were left up to each patient's physician. As it turned out, blood pressure medicines, statins (a family of cholesterol-medicines), and insulin were used more frequently in the control group than in the intervention group. One result of this is that LDL (the most important cholesterol molecule) was lower in the control group.

It's easy to see how this might have happened. Imagine two overweight diabetics with elevated cholesterol. One is in the control group. He's not making much progress losing weight, so his doctor starts him on a statin. Statins have solid evidence that they prevent strokes and heart attacks. The other patient is in the intervention group. He's making good progress losing weight with diet and exercise, so the doctor delays starting the statin, choosing instead to recheck his cholesterol in a few months. Maybe his cholesterol eventually drops or maybe it doesn't but the proven statin therapy is delayed despite the high cholesterol because of the optimism generated by the impressive weight loss. The delayed statin use negates whatever benefit the weight loss would have caused, and the two groups end up with equal numbers of strokes and heart attacks.

To put it another way, I think current medical treatment for high blood pressure, diabetes, and high cholesterol is so effective in preventing strokes and heart attacks that it is very difficult to find an intervention that will decrease cardiovascular risk even further. Perhaps the most positive thing that can be said about the weight-loss group is that it had the same cardiovascular outcomes as the control group which was taking more medications.

So my lesson is that overweight diabetics should diet and exercise, but medications to aggressively lower their blood pressure, sugar and cholesterol should not be delayed due to optimism about their weight loss. Lose some weight, but take your statin.

Learn more:
Disappointing Results for Weight Loss and Diabetes (Wall Street Journal)
Weight loss, exercise didn't affect heart outcomes in Look AHEAD (Internal Medicine News)
Weight loss does not lower heart disease risk from type 2 diabetes (National Institutes of Health)
Cardiovascular Effects of Intensive Lifestyle Intervention in Type 2 Diabetes (NEJM article)
Do Lifestyle Changes Reduce Serious Outcomes in Diabetes? (NEJM editorial)

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. Holding privileges at Cedars-Sinai Medical Center, he is also an assistant clinical professor at UCLA's Department of Medicine. This post originally appeared at his blog.

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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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