Update From the Medical Journals: August 2011
August 30, 2011
By Mary Pickett, M.D.
What's the latest news in the medical journals this month? Find out what your doctor is reading.
Women who are depressed have a higher risk of stroke than other women. This new observation comes from a study that monitored the health of 80,574 women for six years. The study is part of the ongoing Nurses' Health Study. It was published online August 11 in the journal Stroke.
The women were 54 to 79 years old. At the time the study began, none of them had a history of stroke. About 22% of them were depressed or had been depressed in the past.
During the next six years, there were 1,033 strokes. The stroke rate was 29% higher in women with depression or a history of depression compared with women with no depression history. The increased risk was not explained by other risk factors for stroke, which were also assessed in the study.
Women who were taking antidepressant medicines had 39% more strokes than women who were not taking antidepressant medicines. The researchers were not able to say whether the drugs caused the extra risk. The women taking medication may have more severe depression.
Overall this study raised more questions than it answered. We do not know the reason depression is associated with a higher stroke risk. There are several theories. Depression may lead to chemical changes in the brain. Also, depression is more common in women who have health problems such as vascular (artery) disease. Finally, depressed people tend to eat a less healthy diet and to exercise less.
It is helpful to identify and treat depression. We do not yet know whether treatment of depression can improve a person's risk for other medical conditions.
Atrial fibrillation is a heart rhythm condition that slows the blood flow in the left atrium of the heart. This can allow a blood clot to form. If the blood clot travels it can cause a stroke. People who have atrial fibrillation commonly use clot-prevention drugs (also called anticoagulants or blood thinners) to lower their risk for stroke.
Rivaroxaban is the newest drug to prevent clots. The New England Journal of Medicine published findings online on August 10 concerning the safety and benefits of rivaroxaban. In this study, 14,264 patients were randomly assigned to receive either rivaroxaban or the anticoagulant drug warfarin (Coumadin). The stroke rate was 1.7% per year for the rivaroxaban group, and 2.2% for the warfarin group. This was not a significant difference.
In February 2011, the American College of Cardiology, the American Heart Association and the Heart Rhythm Society updated the guideline for preventing stroke in people with atrial fibrillation. A new clot-prevention drug called dabigatran (Pradaxa) was included as a treatment option. Rivaroxaban is a very similar drug to dabigatran. It's very likely that the next version of the guideline will include rivaroxaban. Warfarin, dabigatran and rivaroxaban are strong clot-prevention drugs; aspirin provides mild stroke prevention.
Warfarin is the drug that is traditionally used for stroke prevention. But it's a tricky drug to use. It requires close monitoring with blood tests at least every three weeks to make sure the dose is correct. Certain drugs and foods can temporarily cause warfarin to either be less effective than needed, or more hazardous. Even with frequent blood tests, only about 60% of patients don't need their doses adjusted at each check.
Dabigatran and rivaroxaban, unlike warfarin, do not require frequent blood tests for monitoring. But it is not clear that these will be better therapies. While they save on laboratory costs, they are very expensive. (Dabigatran costs about $10 per day, and rivaroxaban will probably have a similar cost).
Some experts are also worried that it may be more difficult to treat overdose or bleeding complications from dabigatran and rivaroxaban. That's because these side effects can't easily be reversed in an emergency. If warfarin has made the blood too thin, doctors can use vitamin K or neutralizing "binders" to reverse the effect.
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.