Update From the Medical Journals: July 2010 - What Your Doctor Is Reading - Harvard Commentaries

What's the latest news in the medical journals this month? Find out what your doctor is reading.

Statins Benefit Heart Patients, But May Not Be Beneficial for People With Healthy Hearts
Low Vitamin D Levels May Lead to Memory Loss and Decline in Brain Function
More News in Brief: FDA Committee Frowns On Rosiglitazone; ACE Inhibitor and "ARB" Drugs Don't Mix Well with Common Antibiotic; Stem Cells Cure Blindness From Chemical Burns

A new study suggests that if you have an above-average risk for a heart attack, but have never had one, taking a statin drug to lower your cholesterol will not help you to live longer.

There was no sign that these drugs can prevent early deaths except in people who already have had heart attacks, strokes or related events. The study, published in the Archives of Internal Medicine on June 28, combined the data from 65,229 patients who were involved in 11 previous studies. (Combining data from multiple studies into one large study is a research technique called meta-analysis.) The analysis included people with a variety of factors that increase the risk of heart disease. These included smoking, diabetes and high LDL ("bad") cholesterol.

Statin drugs include atorvastatin (Lipitor), simvastatin (Zocor), and several other popular medicines. People with prior heart attacks tend to live longer if they take a statin drug. But this new meta-analysis purposely did not include people who had ever had a heart attack or other event. It only included people who have risk factors for heart disease who were randomly assigned to take either a statin or a placebo (fake pill).

The researchers looked at data during an average of 3.7 years when people were taking either a statin or placebo pill. They found that statins lowered LDL cholesterol compared with placebo pills. However, they found no difference in death rates from all causes between healthy people who took statins and healthy people who did not. The follow-up time — 3.7 years — is too short for us to expect dramatic results, but a result of "zero" benefit is important. It may mean that statins are not worth using by people who have not "officially" been diagnosed with heart disease.

The National Cholesterol Education Program (NCEP) last updated its official recommendations for cholesterol treatment in 2004. Data from this meta-analysis will certainly be reviewed, and guidelines for preventive use of statins will be reconsidered.

It is reasonable to use a statin drug if your LDL cholesterol is above 160 milligrams per deciliter (mg/dL). It is also probably reasonable to use a statin if you have two or more risk factors for heart disease and an LDL level higher than 130 mg/dL. People with lower cholesterol numbers or fewer risks might want to watch for the new NCEP guidelines, which should be released in draft form in Spring, 2011.

Vitamin D is needed for strong bones. Low blood levels of vitamin D have been linked to a greater risks for falls, cancer and infections. Now, two studies show that vitamin D may help the brain to stay in good health as we age.

A study published in the July 12 issue of Archives of Internal Medicine links low vitamin D levels to memory loss and major declines in thinking and learning. This study looked at vitamin D levels of 858 adults older than 65. Over a period of six years, the researchers tested the study subjects' mental abilities several times. People who had low vitamin D levels were 60% more likely than others to lose their thinking skills over time. Thinking, learning and memory test scores got lower. The adults with low vitamin D levels were also 31% more likely to lose skills in organizing and planning. (These abilities are known as "executive function.") In this study, vitamin D was considered low if it was below 25 nanomoles per liter.

A second study was published in the July issue of the Archives of Neurology. It used data and blood samples collected from 3,173 people in Finland over most of their adulthood. Researchers divided the adults into four groups of equal size, based on how high or low their vitamin D levels were when they were enrolled in the study. They compared the group with the highest vitamin D levels to the group with the lowest vitamin D levels. People with the lowest vitamin D levels had a 67% higher risk of developing Parkinson's disease in the future. (Parkinson's disease causes a tremor in the hands or head and difficulty with movement.) The researchers were not sure whether vitamin D levels had a direct effect on the risk for Parkinson's disease, or whether they were simply a marker for some other difference in health or habits that was resonsible for the increased risk.

Researchers are not sure why vitamin D appears to be important to brain function. It may work by improving the immune system, by clearing damaging substances out of the brain, or by acting as an antioxidant to prevent harm to brain cells. Neither of these studies proved that taking extra vitamin D could protect the brain. Still, it seems prudent for all of us to make sure we get enough vitamin D. Daily supplements of 400 to 600 IU of vitamin D are probably adequate for most adults. If you are older than 65, have thin bones, rarely get out in the sun, or exclude milk products from your diet, you may need a larger daily dose of vitamin D as a supplement. Your doctor can test your vitamin D level by doing a blood test.

FDA Committee Frowns on Rosiglitazone. On July 14 an advisory committee to the U.S. Food and Drug Administration (FDA) recommended stronger warnings on the label for the diabetes drug rosiglitazone (Avandia). In light of the committee's negative view about the drug's safety, the FDA is considering whether to re-label this drug or to remove it from the market entirely. Rosiglitazone lowers blood glucose by making a person with diabetes more sensitive to insulin. However, when the drug's safety was analyzed in 2007, people taking rosiglitazone had 43% more heart attacks than people who were treated with other diabetes medicines or with a placebo. Since one of the major goals in diabetes treatment is to lower heart attack risk, many doctors stopped using rosiglitazone after that initial report. Now, additional drug safety data have increased concern. While it considers the new data, the FDA has also put on hold a study that would compare the safety of rosiglitazone with a closely related drug, pioglitazone (Actos). Experts think pioglitazone is safer than rosiglitazone, and the FDA has not identified concerns about pioglitazone.

ACE Inhibitor and "ARB" Drugs Don't Mix Well with Common Antibiotic. Taking the antibiotic treimethoprim-sulfamethoxazole (Septra, Bactrim) and either an ACE inhibitor or angiotensin receptor blocker (ARB) can result in a dangerously high level of potassium in the blood, according to a study in the June 28 issue of the Archives of Internal Medicine. ACE inhibitors and ARB drugs are commonly used to treat high blood pressure and prevent kidney damage from diabetes. ACE inhibitors include lisinopril (Zestril, Prinivil), enalapril (Vasotec), benazapril (Lotensin) and others; angiotensin receptor blockers (ARBs) include losartan (Cozaar), valsartan (Diovan) and others. The researchers analyzed 4,148 ocassions when people in Canada were hospitalized for high potassium levels (also called hyperkalemia.) High potassium can occur with these blood pressure drugs even when they are not combined with the antibiotic, so these drugs need periodic blood tests to monitor potassium. According to the analysis, taking trimethoprim-sulfamethoxazole made it seven times more likely that a person on one of these blood pressure drugs would have dangerously high potassium. This sulfa-based antibiotic is used frequently for urinary tract infections, skin infections, including resistant "staph" infections, and respiratory infections. Doctors may need to avoid prescribing this antibiotic to people who take an ACE inhibitor or "ARB" drug, or monitor your potassium closely during the time you are on the antibiotic. Another solution is to temporarily stop using the other drug while on the antibiotic.

Stem Cells Cure Blindness From Chemical Burns. A success story about stem-cell transplants was published online by the New England Journal of Medicine on July 8. This study used stem cells to treat 106 patients who were blind due to chemical burns to their eyes. Chemical burns damage the cornea, changing it from a clear tissue to a tissue through which you can't see. Normally, the outside edge of the cornea contains stem cells. These can generate new cornea cells that repair areas with minor damage. If chemical burns are severe, the stem cells at the edge of the cornea are killed. In this study, when stem cells were grown in a laboratory and implanted into the eyes of blind patients, more than three out of four patients regained sight.

Mary Pickett, M.D. is an Associate professor at Oregon Health & Science University where she is a primary care doctor for adults. She supervises and educates residents in the field of Internal Medicine, for outpatient and hospital care. She is a Lecturer for Harvard Medical School and a Senior Medical Editor for Harvard Health Publications.