Incidence of Cerebrovascular Diseases
Stroke, after heart disease and cancer, is the third most common
cause of death in the United States. Every year there are in this
country approximately 700,000 cases of stroke—roughly 600,000
ischemic lesions and 100,000 hemorrhages, intracerebral or subarachnoid—
with 175,000 fatalities from these causes. Since 1950,
coincident with the introduction of effective treatment for hypertension,
there has been a substantial reduction in the frequency of
stroke. This was most apparent three decades ago, as treatment for
high blood pressure became a public health focus. Among the residents
of Rochester, Minnesota, Broderick and colleagues documented
a reduction of 46 percent in cerebral infarction and hemorrhage
when the period 1975–1979 was compared with 1950–
1954; Nicholls and Johansen reported a 20 percent decline in the
United States between 1968 and 1976. Both sexes shared in the
reduced incidence. During this period, the incidence of coronary
artery disease and malignant hypertension also fell significantly.
By contrast, there has been no change in the frequency of aneurysmal
rupture. Interestingly, despite the continued improvement
in the treatment of hypertension, the incidence rate of stroke for
the period 1980–1984 was 17 percent higher than that for 1975–
1979, a feature attributed by Broderick and coworkers to the widespread
use of computed tomography (CT), which increased the
detection of less severe strokes. In the last decade, according to the
American Heart Association, the mortality rate from stroke has
declined by 12 percent, but the total number of strokes may again
be rising.
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