Incidence of ischemic stroke in patients aged 65 and older decreased by 41 percent between 1988 and 2008, according to data published in the July issue of the American Journal of Medicine. Hemorrhagic stroke decreased 16 percent in the same time period.
The research team led by Margaret C. Feng, MD, MPH, of the University of California, San Francisco Division of Hospital Medicine, offered that the decreases may be a result of increased use of antihypertensives and statins.
Feng et al reported that the crude 30-day mortality rate for hemorrhagic stroke decreased from 43.4 percent to 42.1 percent between 1988 and 2008. The ischemic stroke 30-day mortality rate decreased from 16.2 percent to 15.2 percent. Risk-adjusted mortality for ischemic stroke decreased from 15.9 percent to 12.7 percent while hemorrhagic stroke decreased from 44.7 percent to 39.3 percent.
Thirty-day mortality rates in men and women also saw decreases. In men, ischemic stroke went from 16.3 percent to 11.2 percent and hemorrhagic stroke from 45.2 percent to 38.8 percent. In women, ischemic stroke rates decreased from 15.6 percent to 13.6 percent while hemorrhagic stroke rates decreased 44.4 percent to 39.6 percent.
Rates of ischemic stroke overall decreased from 927 per 100,000 in 1988 to 545 per 100,000 in 2008. Rates for hemorrhagic stroke overall decreased from 112 per 100,000 to 94 per 100,000. Decreases were seen in both sexes for overall stroke.
Transient ischemic attack incidence decreased from 417 per 100,000 in 1988 to 234 per 100,000 in 2008.
Concurrent with these trends, an increased use of statins and antihypertensive medications was noted. Statin use in the general public increased from 4 percent in 1992 to 41.4 percent in 2008, while antihypertensive use increased from 53 percent in 1992 to 73.5 percent in 2008.
However, with the decreases in overall incidence of stroke and increased use of medications, predicted stroke risks actually increased over the same period, from a mean Framingham risk score of 8.3 percent during 1988 through 1994 to 8.8 percent in the subsequent period. Increases may be attributable to parallel increases in rates of diabetes. Other risks such as cigarette smoking, measured systolic blood pressure and total cholesterol values have decreased over time.
The risk with atrial fibrillation has also increased from 8.3 percent to 8.5 percent. The research team wrote that this may be attributable to limitations in the use of the Framingham risk model.
Fang et al proposed that rates possibly are dropping due to better risk factor modification through improved means of controlling blood pressure and cholesterol, but they hesitated to make a full causal relationship. “The decline in stroke rates occurred over a period of significant uptake in the use of medications that attenuate stroke risk,” they wrote. “Antihypertensive medications reduce the risk of stroke by approximately 32 percent, and statins reduce the risk of stroke by approximately 21 percent.”