Copyright American Stroke Association
High and even high-normal body mass index (BMI) were linked to increased ischemic stroke risk, regardless of whether or not individuals had diabetes.
Overweight and obese adolescent groups in the study had a roughly two- to threefold increased risk of ischemic stroke, which was apparent even before age 30 years in the study that was based on records of Israeli adolescents evaluated prior to mandatory military service.
These findings highlight the importance of treating and preventing high BMI among adolescence, study coauthor Gilad Twig, MD, MPH, PhD, said in a press release.
“Adults who survive stroke earlier in life face poor functional outcomes, which can lead to unemployment, depression and anxiety,” said Dr. Twig, associate professor in the department of military medicine in The Hebrew University in Jerusalem.
The costs of stroke prevention and care, already high, are expected to become even higher as the adolescent obesity prevalence goes up, fueling further increases in stroke rate, Dr. Twig added.
This is believed to be the first study showing that stroke risk is associated with higher BMI values in both men and women, not just men, Dr. Twig and coauthors said in their article, published May 13, 2021 in the journal Stroke. Previous studies assessing the stroke-BMI relationship in adolescents were based on records of Swedish men evaluated during military conscription at age 18.
In the present study, Dr. Twig and coauthors assessed the linkage between adolescent BMI and first stroke event in 1.9 million male and female adolescents in Israel who were evaluated 1 year prior to mandatory military service, between the years of 1985 and 2013.
They cross-referenced that information with stroke events in a national registry to which all hospitals in Israel are required to report.
The adolescents were about 17 years of age on average at the time of evaluation, 58% were male, and 84% were born in Israel. The mean age at the beginning of follow-up for stroke was about 31 years.
Over the follow-up period, investigators identified 1,088 first stroke events, including 921 ischemic and 167 hemorrhagic strokes.
A gradual increase in stroke rate was seen across BMI categories for ischemic strokes, but not so much for hemorrhagic strokes, investigators found.
Hazard ratios for first ischemic stroke event were 1.4 (95% confidence interval, 1.2-1.6) for the high-normal BMI group, 2.0 (95% CI, 1.6-2.4) for the overweight group, and 3.5 (95% CI, 2.8-4.5) for the obese group after adjusting for age and sex at beginning of follow-up, investigators reported.
When the adjusted results were stratified by presence or absence of diabetes, estimates were similar to what was seen in the overall risk model, they added.
Among those young adults who developed ischemic stroke, 43% smoked, 29% had high blood pressure, 17% had diabetes, and 32% had abnormal lipids at the time of diagnosis, the reported data showed.
The clinical and public health implications of these findings could be substantial, since strokes are associated with worse medical and socioeconomic outcomes in younger as compared with older individuals, according to Dr. Twig and coauthors.
Younger individuals with stroke have a higher risk of recurrent stroke, heart attack, long-term care, or death, they said. Moreover, about half of young-adult stroke survivors have poor functional outcomes, and their risk of unemployment and depression/anxiety is higher than in young individuals without stroke.
One limitation of the study is that follow-up BMI data were not available for all participants. As a result, the contribution of obesity to stroke risk over time could not be assessed, and the independent risk of BMI during adolescence could not be determined. In addition, the authors said the study underrepresents orthodox and ultraorthodox Jewish women, as they are not obligated to serve in the Israeli military.
The study authors had no disclosures related to the study, which was supported by a medical corps Israel Defense Forces research grant.