 | What Your Doctor Is Reading | | |
Update From the Medical Journals: April 2008
April 30, 2008  By Mary Pickett, M.D.
Harvard Medical School What's the latest news in the medical journals this month? Find out what your doctor is reading. DASH Diet Helps Prevent Heart Attacks and Strokes A study that has been tracking the eating habits of more than 88,000 nurses over 24 years suggests that a special diet called DASH, which reduces blood pressure, can significantly lower the risk for heart attack and stroke. The DASH diet's full impact on heart disease and stroke has been unknown. This study was published April 14 in the Archives of Internal Medicine. It is part of the ongoing national research effort called the Nurses' Health Study. DASH stands for the Dietary Approaches to Stop Hypertension. The diet includes twice as many fruits, vegetables and whole grains as the average American diet. It is low in salt, saturated fat, cholesterol and total fat. The eating plan also recommends that you get a portion of your daily protein from beans, lentils or other legumes, nuts and low-fat dairy foods. The Nurses' Health Study has been collecting information about the women's diets since 1980. At that time, the women were between 34 and 59 years old and had no history of heart disease, stroke or diabetes. On seven different occasions researchers have surveyed the nurses for details about their diet, lifestyles and medical information. They also reviewed medical records if they received permission to do so. Based on the responses, the researchers evaluated each woman's diet and assigned a "score." Points were added when women reported that they frequently ate fruits, vegetables, legumes or nuts, low-fat dairy items and whole grain foods. Points were subtracted when women reported regularly eating high-fat dairy foods or red meats. The higher a woman's score, the more similar her diet was to what we now call the DASH diet. (When the study began, the DASH diet hadn't yet been described and recommended.) There have been 2,129 non-fatal heart attacks, 976 deaths from heart disease and 2,317 strokes over the 24 years of the study. Researchers wanted to know if these events occurred more often among women who had lower DASH scores. They compared women who had DASH scores in the top 20% with women who had scores in the bottom 20%. They found that the group of women with the higher scores — those whose diet most closely followed the DASH diet — had 24% fewer fatal and non-fatal heart attacks and 18% fewer strokes than the group of women with the low DASH scores. This was not a "randomized" study: It didn't assign one group of women to follow a specific diet plan and compare them to another group that followed their normal plan. For this reason, it is not possible to say with certainty that the diet was the reason women with high DASH scores had better health outcomes — perhaps the women who ate so carefully had other health-promoting habits as well. Still, it provides the best evidence that we have so far that the DASH diet is a healthy way to eat. Back to top Larger Waist Size Raises Risk for Dementia New research shows that "apple-shaped" adults who had an oversized waist at age 40 to 45 are now showing signs of dementia at greatly increased rates. This research was published online on March 26 by the journal Neurology. The study began in the 1970s and enrolled 6,583 men and women in their 40s. Waist size was measured using an instrument called a caliper. A measurement greater than 25 centimeters was considered oversized. About 35 years later, 16% of these individuals had developed Alzheimer's disease or another form of dementia. The dementia was most heavily concentrated among the people who had entered middle-age with oversized waists. People with larger waists had about double the dementia risk of people with normal or small waists. This was true even if their body mass index (BMI) was normal. People who were obese (BMI over 30) and also had an abnormally large waist had 3 1/2 times the dementia risk as a person with normal waist size and normal BMI. This is stunning news. Until now, we have had few ways to predict and prevent dementia. The study didn't prove that obesity causes dementia. However, the association was so great that experts are betting that reversing obesity is likely to reverse the risk for dementia. Abdominal obesity increases the risk of heart disease, diabetes, high blood pressure, liver inflammation and scarring, and unhealthy cholesterol levels. Studies have also shown that a high BMI can lead to stroke, sleep apnea, some cancers, osteoarthritis, gallstones and early death. Americans fear dementia more than any of these conditions. A link between waist size and dementia should be a powerful motivator for us to slim down. Back to top Osteoporosis Drug May Double Risk for Irregular Health Rhythm A study published April 28 in the Archives of Internal Medicine revealed that the osteoporosis drug alendronate (Fosamax) appears to increase the risk for atrial fibrillation. Atrial fibrillation is an irregular heart rhythm that can sometimes cause dizziness, heart stress, or strokes. New worries about bone drugs and heart problems developed last year after a study in the May 3, 2007 issue of the New England Journal of Medicine showed that while a once-yearly injection of the osteoporosis drug zolendronic acid (Reclast) reduced the risk of spine and hip fractures, it had an unexpected side effect. The women who received the injection had about one and a half times the usual risk for developing atrial fibrillation, which required emergency treatment for some women. This finding surprised researchers and prompted them to review data for the more commonly used osteoporosis treatment medicine, alendronate (Fosamax). Researchers from the University of Washington sorted through medical charts of women members from a health care organization in Washington state. They identified 719 women who had atrial fibrillation and 966 women who did not. Both groups of women were of similar ages and had similar blood pressure measurements. When the medication lists were reviewed, 6.5% of the women who had atrial fibrillation had used alendronate at some time in their post-menopausal years. By comparison, 4.1% of the women without atrial fibrillation had taken alendronate. Researchers were then able to calculate that the risk of atrial fibrillation was nearly doubled (1.86 times the normal risk) for women who used alendronate. This included women who currently took the drug and women who had previously taken it but had discontinued it prior to the study. The researchers estimated that about 3% of all new atrial fibrillation cases in post-menopausal women could be blamed on alendronate use. This news will change the recommendations that many doctors make, relating to osteoporosis treatment. The risk for atrial fibrillation is small, but it is serious. Alendronate and other similar medications will still be useful for treating women with severe osteoporosis. For women who have mild osteoporosis or less significant bone thinning ("osteopenia"), drug treatment will almost certainly need to be reconsidered. Back to top More News in Brief - High Blood Urate Levels Are Linked to Slower Progression of Parkinson's. On April 14, the Archives of Neurology published a study online that found a link between blood levels of urate and the progression of Parkinson's disease. Urate, a form of uric acid, is a normal waste product of the body. Researchers measured the urate levels of 804 people with Parkinson's disease at the start of the study. Then they divided people into five groups depending on their urate level. At that time, all of the participants did not yet need medication to treat symptoms because their disease was mild. Over the three years of the study, however, 61% of the patients needed to begin medication because their disease got worse. Urate levels seemed to predict whether Parkinson's would be stable or worsen during the three years. People who had a urate level at or above 6.7 milligrams per deciliter (mg/dL) were only half as likely to need medication as people who had a urate level less than 4.3 mg/dL. This study neither proves that urate prevents Parkinson's progression, nor provides us with definite new strategies for managing Parkinson's disease. However, it opens a significant new area of research that may eventually enable doctors to better understand the disease and to delay or prevent progression.
- This Year's Flu Shot Is Less Effective Than Usual. The Centers for Disease Control and Prevention (CDC) reported that this year's flu shot has been less effective than usual at preventing the flu. Findings from the surveillance study were published April 18 in the Morbidity and Mortality Weekly Report. CDC researchers swabbed the throats of 639 people who came to their doctors with cough and congestion symptoms and tested them for flu. Thirty-one percent of these patients were confirmed to have influenza (flu). Among those who tested positive for flu, 19% had received the flu shot. Among those who tested negative for the flu, 39% had received the flu shot. This means that this year's flu shot prevented the flu after exposure to the virus only 44% of the time. A 44% effectiveness rate is worthwhile — imagine how satisfied we would be with an equally simple treatment that could prevent other illnesses, such as cancer or heart disease, by 44%. Still, the results are disappointing compared with the usual 70% to 90% effectiveness of flu shots.
Back to top Mary Pickett, M.D. is a lecturer for Harvard Medical School and an assistant professor of medicine at Oregon Health & Science University. At OHSU, she is a director of student programs and she oversees teaching of students and medical residents. She practices general internal medicine in Portland, Ore.
| 
