American adults suffer a higher prevalence of stroke than Europeans, says a study presented at the American Stroke Association’s International Stroke Conference 2008. American men are 61 percent more likely to have suffered a stroke than their European counterparts, and U.S. women are twice as likely as European women to have had a stroke in their lifetimes.

In the analysis of worldwide stroke statistics, U.S. numbers indicated that African-Americans are at an especially high risk, being nearly three times more likely to have suffered a stroke in their lifetimes. “Other Americans” placed second. Residents of southern and western states were more likely to have suffered a stroke than those of other states.

A previous study led by George Howard, Dr.P.H. (doctor of public health), of the University of Alabama at Birmingham identified the so-called “stroke belt” states: Alabama, Arkansas, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, and Tennessee, plus Florida and Virginia. Howard also identified other states with large black populations as those at an especially high risk. These include California, Illinois, Indiana, Maryland, Michigan, New Jersey, New York, Ohio and Pennsylvania.

Among Europeans, northern countries were more likely to have populations affected by stroke, with Denmark and Sweden having the highest prevalence. This effect is what study author Mauricio Avendano, Ph.D., called a “north-south gradient.”

Interestingly, economics also play a role in the study results, with discrepancies between the rich and poor. “Most of this gap is among relatively poor Americans who were, in our data, much more likely to have a stroke than poor Europeans, whereas the gap in stroke prevalence is less marked between rich Americans and rich Europeans,” said Avendano in a public statement. 

“The strength of these surveys is that the questionnaires were explicitly designed to be fully comparable across all countries, and the samples were drawn to be representative of the entire population in each country,” said Avendano, a research fellow in public health at the Erasmus Medical Center in Rotterdam, The Netherlands.

“Many risk factors for stroke, including blood pressure and smoking, have generally increased among women but remained stable among men,” Avendano said publicly. “This may explain why the gap in stroke prevalence between men and women is less marked than before. In fact, in some age groups and populations such as France, women may have higher prevalence of stroke than men.” However, overall results showed that women are 25 percent less likely to have a stroke than men.  

After adjusting for age, research indicated the least prevalence of stroke in the southern Mediterranean European countries of Spain, Italy and Greece. “Southern Mediterranean countries have a diet rich in vegetables, fruits and fish and lower in fats, which partly explains why heart disease is so much lower in these populations than in northern Europe and the United States,” Avendano said publicly.

“However, for stroke, the picture is more complicated. For instance, although Italy has relatively low stroke prevalence, former studies indicate that Italians have a similar or higher stroke incidence rate than people in other European countries or the United States. Thus, the results on prevalence may also reflect poor stroke survival in Italy, which will result in a lower prevalence of stroke,” he explained.

This is because high prevalence can only be reflected in living populations. “If everyone has a disease and everyone survives, then prevalence is 100%," American Stroke Association spokesman Larry Goldstein, MD told WebMD. The U.S. has actually seen a 25 percent drop in the stroke-related deaths in recent years, said Goldstein. “Incidence” refers to the estimated number of new cases, usually assessed per year.  

“Beyond the contribution of specific risk factors, policies that differ dramatically between Europe and the United States may play a role,” Avendano said publicly. This includes healthcare access, which is universal in Europe but not in the United States, and “the preventive orientation of some European systems aimed at tackling stroke risk factors, as opposed to the U.S. healthcare system, which focuses more on treatment and may actually be more successful in keeping stroke cases alive.”

There is some hope for the U.S., however. According to Avedano, "the proportion of current smokers is lower in the U.S. So going forward we could see a positive effect of that trend."