The number of older Americans who suffer strokes and the number of younger Americans who die from strokes is on the decline, but the growing rates of obesity threaten to reverse the trend, experts say.
A recent study found a 24 percent overall decline in first-time strokes in each of the last two decades and a 20 percent overall drop per decade in deaths after stroke.
The decline in stroke risk was concentrated mainly in the over-65 set, however, with little progress in reducing strokes among younger people.
In contrast, the drop in stroke-related deaths was primarily found among those under age 65, with mortality rates holding firm in older people.
“We can congratulate ourselves that we are doing well, but stroke is still the No. 4 cause of death in the United States,” says coauthor Josef Coresh, professor of epidemiology at Johns Hopkins University.
“This research points out the areas that need improvement. It also reminds us that there are many forces threatening to push stroke rates back up and, if we don’t address them head-on, our gains may be lost.”
Obesity and stroke
Coresh says he worries what the obesity epidemic, which began in the 1990s, will mean for stroke trends. As millions more people are diagnosed with hypertension and diabetes—which often go hand-in-hand with obesity—they will face increased risk for stroke, he says.
For the study, published in the Journal of the American Medical Association, researchers used data from the Atherosclerosis Risk in Communities study, which tracked residents of four US communities who were between the ages of 45 and 64 when the study began in the late 1980s.
In this analysis, they followed 14,357 participants who had no history of stroke in 1987. The research team looked for all stroke hospitalizations and deaths from then to the end of 2011.
Seven percent of the study sample (1,051 people) had a stroke during that period. Of those, 10 percent died within 30 days. Another 21 percent, 40 percent, and 58 percent died within one year, within five years, and by the end of the study in 2011.
800,000 strokes a year
Each decade, the number of deaths occurring within 10 years of a stroke was reduced by roughly eight deaths per 100 cases. The decrease was not across the board; it was primarily the result of stroke victims under the age of 65 surviving longer.
While they varied by age, the results were similar across race and gender, a finding that encouraged researchers since a previous study suggested African-American stroke rates were not improving.
Decreases in stroke incidence and mortality are partly due to more successful control of risk factors such as blood pressure or smoking and to the wide use of statin medications to control cholesterol. An increase in diabetes likely acted in the opposite direction, however, pushing stroke rates back up to some extent.
Stroke severity and improvements in treatment likely also impacted the data, though the study could not measure the exact role they played.
The age disparities suggest areas where physicians and researchers may want to focus in the future to prevent strokes in those under 65 and reduce deaths in those over 65. Nearly 800,000 Americans suffer strokes each year; of those, about 600,000 are first-time strokes.
Pay attention to subgroups
“Stroke is not only one of the main causes of death, but a leading cause of long-term disability in adults. Therefore, prevention is the best strategy,” says study leader Silvia Koton, a visiting faculty member at the Bloomberg School and incoming nursing chair at Tel Aviv University.
The number of US death certificates listing stroke as the underlying cause of death has decreased for a long time. Only studies such as this one, however, can distinguish whether the decline is due to a reduction in the number of strokes or whether people are just living longer after having them, researchers say.
The new study also confirmed the occurrence of each stroke by reviewing each medical chart using uniform criteria.
“Since rates are not equally falling across the board, physicians and policymakers need to pay closer attention to specific subgroups,” Koton says. “These data are also helpful in monitoring the results of how we care for people of all ages, hopefully helping them even before they have a stroke.”
The National Heart, Lung and Blood Institute supported the research.
Source: Johns Hopkins University