, with a greater than 50% reduction in risk.
Lead study author Raed A. Joundi, MD, DPhil, of the University of Calgary (Alta.), said he expected results to show exercise was beneficial, but was surprised by the magnitude of the association between physical activity and lower mortality risk.
The impact of physical activity also differed significantly by age; those younger than 75 had a 79% reduction in mortality risk, compared with 32% in those age 75 and older.
“This is even after adjusting for factors such heart disease, respiratory conditions, smoking, and other functional limitations,” said Dr. Joundi.
The study was published online Aug. 11 in the journal Neurology.
For this analysis, the researchers used data on a cohort of people across Canada (excluding the province of Quebec) over 3-9 years. The 895 patients with prior stroke averaged 72 years of age, while the 97,805 in the control group had an average age of 63.
Weekly physical activity averages were evaluated using the self-reporting Canadian Community Health Survey, which was linked with administrative databases to evaluate the association of physical activity with long-term risk for mortality among stroke survivors, compared with controls.
Physical activity was measured in metabolic equivalents (METs); meeting minimum physical activity guidelines was defined as 10 MET-hours/week.
During the study period, more stroke patients than controls died (24.7% vs. 5.7%). However, those who met the physical activity guideline recommendations of 10 MET-hours/week had a lower mortality, both in the stroke survivor group (14.6% vs. 33.2%; adjusted hazard ratio, 0.46; 95% confidence interval, 0.29-0.73) and among control participants (3.6% vs. 7.9%; aHR 0.69; 95% CI, 0.62-0.76).
The largest absolute and relative reduction in mortality was among stroke respondents younger than 75 (10.5% vs. 29%; aHR, 0.21; 95% CI, 0.10-0.43), the researchers note.
There was a significant interaction with age for the stroke patients but not the control group.
“The greatest reduction in mortality was seen between 0 and 10 METs per week … so the main point is that something is better than nothing,” said Dr. Joundi.
Exercise guidelines for the future
Although current guidelines recommend physical activity in stroke survivors, investigators noted that these are largely based on studies in the general population. Therefore, the aim of this research was to get a better understanding of the role of physical activity in the health of stroke survivors in the community, which could ultimately be used to design improved public health campaigns and physical activity interventions.
Given that this is a large study of stroke survivors in the community, Dr. Joundi hopes the results will influence future activity guidelines for those who have suffered a stroke.
“We found a log-linear relationship between physical activity and mortality such that 10 MET-hours/week was associated with large reductions in mortality with most benefit achieved by 20 MET-hours/week,” the authors concluded. “These thresholds could be considered for use in future guidelines for stroke.”
Clinical trials are underway to provide evidence for the implementation of exercise programs after stroke, they add, and offering physical activity programs to stroke survivors in the community “is an increasing priority in the U.S., Canada, and Europe.”
“People are at higher risk of death early on after a stroke but also months and years later, so if we can identify a relatively low-cost and easy intervention like physical activity to improve health and reduce the risk of death for stroke survivors it would be important,” Dr. Joundi said.