The research was led by a team from the Johns Hopkins Bloomberg School of Public Health in Baltimore, MD, and is published in JAMA.
Overall, the findings revealed a 24% drop in first-time strokes in both of the last 2 decades and a 20% drop per decade in deaths following a stroke.
Though still the number 4 cause of death in the US, stroke rates have declined over the past 20 years.
"We can congratulate ourselves that we are doing well," says Dr. Josef Coresh, professor of epidemiology at Johns Hopkins, "but stroke is still the No. 4 cause of death in the US."
He adds that their research "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."
To conduct their study, the team used data from the Atherosclerosis Risk in Communities (ARIC) study, which is a prospective study involving 15,792 participants in the US, who were between the ages of 45-64 at the start of the study in the 1980s.
In total, the researchers followed 14,357 stroke-free people in 1987 and assessed all stroke hospitalizations and deaths between that year and 2011.
Better control of risk factors may be contributing factor
Of the study sample, 7% had a stroke during that time, and of those people, 10% died within 30 days, the team says. Additionally, 21%, 40% and 58% died within 1 year, 5 years and by the end of 2011, respectively.
Each decade, the number of deaths that occurred within 10 years of a stroke decreased by around 8 deaths per 100 cases. The team notes that this reduction was mostly due to stroke victims under the age of 65 surviving longer.
And these results were similar across all races and genders, which surprised the researchers, as a recent study suggested African-American stroke rates were not getting better.
The team discovered that the reduction in stroke incidence and mortality is related to better control of risk factors, including blood pressure, smoking cessation and the use of statins for controlling cholesterol.
Still, echoing Dr. Coresh fears, the researchers say a boost in diabetes most likely worked against stroke rates, pushing them up - but to a lesser extent. Although the study could not account for the exact role they played, the team says stroke severity and treatment improvements likely affected the outcome.
Dr. Silvia Koton, a visiting faculty member at Johns Hopkins, says:
"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."
'Specific subgroups need more attention'
The researchers say the decline in stroke risk was mainly found in people over the age of 65 and that the risk of stroke among young people did not improve much. However, the drop in deaths related to stroke was mostly found in those under 65, whereas mortality rates remained relatively stable in the older group.
As such, the team says these age disparities point to areas where researchers and doctors could focus going forward to prevent strokes and reduce deaths.
Though national data show that death certificates citing stroke as the cause of death have declined, the researchers say only studies like theirs can determine whether this decrease is due to a fall in the number of strokes or whether people are simply living longer after having them.
In their study, the team confirmed each stroke by reviewing every medical chart using consistent criteria, and they focused on deaths from all causes, as many patients die from other causes following a stroke.
"Since rates are not equally falling across the board," Dr. Koton says, "physicians and policymakers need to pay closer attention to specific subgroups."
Medical News Today recently reported on a study from the American Heart Association's journal Stroke, which suggested that psychological stress increases the risk of stroke.