Risk of stroke greater for women than men among older patients diagnosed with atrial fibrillation

May 8, 2012

In a study that examined use of the anticoagulant medication warfarin and risk of stroke following a diagnosis of atrial fibrillation in older patients, women, especially those 75 years or older, had a higher risk of stroke than men, regardless of their risk profile and use of warfarin, suggesting that current anticoagulant therapy to prevent stroke might not be sufficient for older women, according to a study in the May 9 issue of JAMA.

" (AF) is the most common cardiac arrhythmia, accounting for approximately one-third of hospitalizations for disturbances. It has been estimated that 2.2 million people in the United States and 4.5 million in the European Union have paroxysmal or persistent AF. Patients with AF have a 5-fold increase in the risk of stroke compared with the general population; therefore, antithrombotic agents are prescribed to reduce this risk. Sex-based differences related to AF have been identified, the most concerning being that women with AF have an increased risk for , including stroke," according to background information in the article. It has been suggested that underutilization of oral anticoagulation treatment among women has been a contributing factor to this increased risk.

Meytal Avgil Tsadok, Ph.D., of the McGill University Health Center, Montreal, and colleagues compared usage patterns of warfarin and subsequent between men and women 65 years or older with AF. The study included patients admitted to the hospital with recently diagnosed AF in the , Canada, from 1998-2007, using administrative data with linkage between , physicians, and prescription drug claims databases.

The cohort comprised 39,398 men (47.2 percent) and 44,115 women (52.8 percent). At admission, women were older (74.2 percent of women were older than 75 years, compared with 61.4 percent of men) and had a higher CHADS2 (, hypertension, age 75 years or older, diabetes mellitus, prior stroke or transient ischemic attack) score than men. Warfarin prescription rates were slightly higher among women compared with men (60.6 percent in women vs. 58.2 percent in men); women tended to have more prescriptions filled for warfarin within 30 days postdischarge, compared with men. The proportions of warfarin prescriptions filled were slightly increased to 68 percent in women as well as men when prescription rates were assessed within 1 year after discharge. In general, adherence to anticoagulation therapy was relatively high and similar in both sexes.

The researchers found that crude stroke rates were significantly higher in women compared with men (5.8 percent vs. 4.3 percent). The difference between sexes was mainly driven by the rates in the older (75 years and older) patients. "Furthermore, older women had significantly higher rates of stroke than older men, regardless of warfarin use, and women had higher rates of stroke compared with men, regardless of adherence level," the authors write. Analysis indicated that women had a 14 percent higher risk of stroke than men, after adjusting for various factors.

The authors note that it is not yet known why women with AF are more susceptible to stroke. "The increased risk may be attributable to physiology (such as uncontrolled hypertension), vascular biology, genetic factors, hormonal or thromboembolic factors, or psychosocial factors that differ between men and women. We were not able to identify these factors with our database."

"Although epidemiologic studies have investigated sex differences in stroke occurrence, little is known about warfarin effectiveness between men and women in the real-world clinical setting. Our results suggest that elderly women with AF may need to be targeted for more effective stroke prevention therapy. Clinicians should be aware of the elevated stroke risk in older women with AF, and new strategies should be applied to effectively prevent stroke equally in men and women."

Explore further: UK doctors still undertreating atrial fibrillation - major risk factor for stroke

More information: JAMA. 2012;307[18]:1952-1958.

Related Stories

UK doctors still undertreating atrial fibrillation - major risk factor for stroke

October 13, 2011
Despite significant improvements in stroke prevention over the past decade, and a fall in incidence and deaths, UK doctors are still undertreating one of the major risk factors - atrial fibrillation - reveals research published ...

Warfarin related to low rate of residual stroke in patients with atrial fibrillation

March 26, 2012
A review of clinical trials comparing warfarin with other medications for stroke prevention suggests that warfarin was associated with a low risk of stroke or non-central nervous system embolism in patients with nonvalvular ...

Rivaroxaban has less risk of brain bleeding in patients at high risk for stroke

February 2, 2012
For patients with a type of irregular heart beat called atrial fibrillation (AF), a new anti-clotting drug might be better at preventing clot-related strokes while minimizing the risk of causing a bleeding stroke. The research ...

Middle-aged men with upper-normal blood pressure at risk for AF

January 17, 2012
Middle-aged men at the upper end of normal blood pressure had an elevated risk for atrial fibrillation later in life, according to new research in Hypertension: Journal of the American Heart Association.

Recommended for you

Researchers investigate the potential of spider silk protein for engineering artificial heart

August 18, 2017
Ever more people are suffering from cardiac insufficiency, despite significant advances in preventing and minimising damage to the heart. The main cause of reduced cardiac functionality lies in the irreversible loss of cardiac ...

Lasers used to detect risk of heart attack and stroke

August 18, 2017
Patients at risk of heart attacks and strokes may be spotted earlier thanks to a diagnosis tool that uses near-infrared light to identify high-risk arterial plaques, according to research carried out at WMG, University of ...

How Gata4 helps mend a broken heart

August 15, 2017
During a heart attack, blood stops flowing into the heart; starved for oxygen, part of the heart muscle dies. The heart muscle does not regenerate; instead it replaces dead tissue with scars made of cells called fibroblasts ...

Injectable tissue patch could help repair damaged organs

August 14, 2017
A team of U of T Engineering researchers is mending broken hearts with an expanding tissue bandage a little smaller than a postage stamp.

'Fat but fit' are at increased risk of heart disease

August 14, 2017
Carrying extra weight could raise your risk of heart attack by more than a quarter, even if you are otherwise healthy.

Air pollution linked to cardiovascular disease; air purifiers may lessen impact

August 14, 2017
Exposure to high levels of air pollution increased stress hormone levels and negative metabolic changes in otherwise healthy, young adults in a recent study conducted in China. Air purifiers appeared to lessen the negative ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.