The Association between Modifiable Risk Factors and First-ever Ischemic Stroke in Israel: a Case-control Study

Background: Stroke is a leading cause of death and disability. According to the Global Burden of Disease Study 2013, 90.5% of the burden of stroke is attributable to modifiable risk factors. The vast majority of stroke cases are of ischemic origin. In the current study, we aimed to estimate the contribution of potentially modifiable risk factors to ischemic stroke incidence in Israel.

Methods: We conducted a case-control study based on adult cases aged 21-90 with first ever ischemic stroke, reported to the Israeli National stroke registry during 2014-2015, and controls with no history of stroke from the third Israel National Health Interview Survey (INHIS-3), conducted between 2013 and 2015. Controls were matched to cases in a 1:1 ratio by age, sex and ethnicity. Comparable information for cases and controls was available for 5 risk factors: hypertension, diabetes, current smoking, obesity and hyperlipidemia. A conditional logistic regression was used in order to estimate the adjusted odds ratios (ORs) for stroke associated with each individual risk factor. We calculated the population-attributable risk (PAR) for every risk factor, and the composite PAR for all five risk factors, using the adjusted ORs.

Results: The final analysis included 584 matched pairs. The mean age was 69.5 (±12.1), 55.8% were males and 83.0% were Jewish. Ischemic stroke was significantly associated with all five risk factors, and was most prominent for hypertension (OR=3.4, 95% CI 2.5-4.7; PAR=58.7%, 95% CI 51.6%-65.8%). The composite PAR for all 5 risk factors was 77.1% (95% CI 71.5%-82.6%).

Conclusions: Results of our study show that five known and potentially modifiable risk factors can explain 77% of ischemic stroke risk in Israel. Targeting these risk factors, especially hypertension, could result in a marked reduction in the burden of ischemic stroke in Israel. Therefore, primary prevention efforts should be continued and intensified.