Incidence of stroke among people aged 65 years and above has dropped by over 40 percent during the period 1988-2008 in the US, a new analysis of data shows.
This decline is greater than anticipated considering this population's risk factors for stroke, and applies to both ischemic and hemorrhagic strokes.
"Antihypertensive medications reduce the risk of stroke by approximately 32 percent and of statins by approximately 21 percent. Stroke rates decreased sharply after year 1998, approximately when statin use became more prevalent," said Margaret C. Fang, an associate professor of medicine at University of California, San Francisco School of Medicine in the US.
Investigators also found death resulting from stroke declined during the same period.
Preventable but deadly, stroke is the fourth leading cause of mortality in the United States, with approximately 795,000 strokes occurring each year.
The study was constructed to analyse stroke cases over the past two decades, not to investigate causation. However, researchers did find evolving patterns in the risk factors associated with strokes.
Although the prevalence of diabetes mellitus increased over time, other risk factors, such as cigarette smoking, measured systolic blood pressure, and total cholesterol values, decreased.
Investigators analysed occurrence data from a sample of Medicare patients diagnosed as having suffered a stroke.
The analysis showed a reduction in ischemic strokes from 927 per 100,000 in 1988 to just 545 per 100,000 in 2008.
Hemorrhagic strokes decreased from 112 per 100,000 to 94 per 100,000 over the same time period, primarily among men.
Data indicated that stroke mortality also declined. The risk-adjusted 30-day mortality rate for ischemic strokes fell from 15.9 percent in 1988 to 12.7 percent in 2008.
For hemorrhagic stroke, the mortality rates declined slightly from 44.7 percent in 1988 to 39.3 percent in 2008.
The study appeared in The American Journal of Medicine.
