While the prevalence of stroke was similar among men (2.7 percent) and women (2.5 percent), there were great differences among racial and ethnic groups. American Indian/Alaska Natives had the highest rate (6 percent). Blacks had almost double the rate of whites, 4 percent vs. 2.3 percent, respectively. Asians had the lowest rate at 1.6 percent.
Stroke prevalence was almost twice as high in people with less than 12 years of education (4.4 percent) compared to college graduates (1.8 percent).
No one knows for sure why these disparities exist. But a likely explanation is that the higher rates are seen among groups of people with more risk factors.
The second study found delays in getting proper treatment to stroke victims. Only 48 percent of stroke patients arrived at an emergency department within two hours of the onset of symptoms. People who were transported by ambulance tended to get to a hospital within the two-hour window compared with those who didn't go by ambulance -- 56.8 percent vs. 36.2 percent, respectively.
Victims of ischemic stroke -- caused by a clot in a vessel supplying blood to the brain -- are most likely to benefit from clot-busting tissue plasminogen activator (tPA) therapy within two hours of initial symptoms.
The difference between arrival at an emergency department and brain imaging was also shorter for those arriving by ambulance.
Fewer blacks or African-Americans (42.4 percent) arrived within the critical two-hour window than did whites (49.5 percent).
Prevention remains key when it comes to stroke.
"We have acute therapies that work to treat stroke, but most of those therapies only work if given within the first few hours after a stroke," Sacco said. "Therefore, the importance of prevention becomes even greater."
"The major risk factors for stroke are high blood pressure, preexisting heart disease, atrial fibrillation, which is a very common heart rhythm abnormality, high blood cholesterol levels, diabetes, tobacco use, alcohol use, physical inactivity and obesity," Neyer said.
"If people take measures to stay physically active, eat a healthy diet, control their blood pressure and cholesterol levels either through lifestyle modifications or through taking medications, all of those things will lower their risk of having a stroke," he said.
Another expert agreed.
"The bottom line conclusion of this study is that prevention of stroke is the most important thing," said Dr. Ann Miller, director of the Stroke Center at Montefiore Medical Center in New York City. "Prevention is really the best kind of treatment for stroke. Once the process has become established it's just intervening, trying to limit damage, so it's critical to control hypertension, stop smoking and limit alcohol intake."
The CDC has more on stroke prevention.
SOURCES: Jonathan Neyer, epidemiologist, Division for Heart Disease and Stroke Prevention, U.S. Centers for Disease Control and Prevention, Atlanta; Ralph Sacco, M.D., professor and chairman, neurology department, University of Miami Miller School of Medicine; Ann Miller, M.D., director, Stroke Center, Montefiore Medical Center, New York City; May 18, 2007, Morbidity and Mortality Weekly Report