The contribution of potentially modifiable risk factors to acute ischemic stroke burden - Comparing young and older adults.

Stroke is a leading cause of death and disability. In order to estimate the contribution of five modifiable risk factors to acute ischemic stroke (AIS) incidence in Israel, we conducted a case-control study based on first AIS cases aged 21-90 reported to the Israeli National Stroke Registry during 2014-2015, and controls from a national health survey conducted between 2013 and 2015. We calculated the population attributable risk (PAR) of each risk factor and the combined PAR for all risk factors (hypertension, diabetes, current smoking, obesity and hyperlipidemia), in all study population and by subgroups of young adults (age < 55) and older adults (age ≥ 55). The final analysis included 571, 577 and 500 matched pairs for all study population, young adults and older adults, respectively. Among young adults, current smoking and hypertension were the two most contributing risk factors for AIS, accounting for 33.6% (95% CI 27.3-39.9) and 28.9% (95% CI 22.1-35.7) of AIS cases, respectively. Among older adults, hypertension was the single most contributing risk factor for AIS and diabetes was the second most contributing risk factor for AIS, accounting for 64.9% (95% CI 57.3-72.5) and 25.7% (95% CI 17.5-33.9) of AIS cases, respectively. The combined PAR was significantly lower among young adults (PAR = 67.9%), compared with older adults (PAR = 80.7%). The combined PAR for all study population was 80.1% (95% CI 74.0-86.2), indicating that five common and modifiable risk factors explain ~80% of AIS incidence in Israel. Primary prevention strategies targeting these risk factors have the potential to drastically reduce stroke related morbidity and mortality.