Diabetes and high blood pressure are known as stroke risk factors, however, a new study has shown that the amount of risk may decrease as we age.
Study author George Howard, says: “High blood pressure and diabetes are two important risk factors for stroke that can be managed by medication, decreasing a person’s risk.
“Our findings show that their association with stroke risk may be substantially less at older ages, yet other risk factors do not change with age. These differences in risk factors imply that determining whether a person is at high risk for stroke may differ depending on their age.”
28,235 individuals were involved in this study who had never had a stroke. Of this group, 41 per cent were black and 59 per cent were white. Participants were examined for an average of 11 years.
At the beginning of the study participants were interviewed and given physical exams to assess risk factors, which included high blood pressure, diabetes, smoking, atrial fibrillation, heart disease and left ventricular hypertrophy.
Race was considered as part of the assessed risk factors due to the well-known higher stroke risk in Black people.
Participants were followed up by researchers every six months, with strokes being confirmed by reviewing medical records.
During the course of the study, there were 1,405 strokes over 276,074 person-years, which represent both the number of people in the study and the amount of time each person spends in the study.
Participants were divided into three age groups, which were later compared. The age ranges for those groups varied slightly depending on the data being analysed by researchers. The youngest group included participants aged 45-69, the middle group late 60’s to 70s and the oldest group included people 74 and older.
Researchers discovered that people with diabetes in the younger age group were approximately twice as likely to have a stroke as people of similar age who did not have diabetes, while people with diabetes in the older age group had an approximately 30 per cent higher risk of having a stroke than people of similar older age who did not have diabetes.
It was also discovered that those with high blood pressure in the younger age group had an 80 per cent higher risk of having stroke than people of similar age without high blood pressure while that his went down to 50 per cent for people with high blood pressure in the older age group compared to people of similar age without high blood pressure.
Additionally, when researchers examined race as a risk factor, they found a higher stroke risk for Black participants in the younger age group compared to white participants in that group.
The race difference decreased in the older age group. For stroke risk factors such as smoking, atrial fibrillation and left ventricular hypertrophy, researchers did not find an age-related change in risk.
Howard says: “It is important to note that our results do not suggest that treatment of high blood pressure and diabetes becomes unimportant in older age.
“Such treatments are still very important for a person’s health. But it also may be wise for doctors to focus on managing risk factors such as atrial fibrillation, smoking and left ventricular hypertrophy as people age.”
Howard also highlights that even where the impact of stroke risk factors decreases with age, the total number of people with strokes at older ages may still be larger since overall risk of stroke increases with age.
For example, in the younger age group for high blood pressure, researchers estimate that about 2 per cent of people with normal blood pressure had a stroke, compared to 3.6 per cent of people with high blood pressure had a stroke, compared to 9.3 per cent of people with high blood pressure.
A limitation of this research was the participants’ risk factors were assessed only once at the start of the study, and it is possible they may have changed over time.
