Supplementary Material for: Age-Period-Cohort Analysis of Mortality from Ischemic Stroke Attributable to High Systolic Blood Pressure: Trends and 2030 Projections for Turkey and European Subregions

Introduction: High systolic blood pressure (HSBP) is a leading modifiable driver of the global ischemic stroke (IS) burden. We assessed the mortality impact of HSBP-related IS (HSBP-related IS) in Turkey and European sub-regions during 1990-2021 and produced projections for 2030.
Methods: Age-standardized mortality rates (ASMR) and disability-adjusted life-years (ASDR) were extracted from the 2021 Global Burden of Disease dataset. Age-period-cohort (APC) models were used to identify demographic effects. A log-linear regression that included the Sociodemographic Index (SDI) generated the 2030 ASMR projections.
Results: Between 1990 and 2021, ASMR and ASDR fell in Western, Central and Eastern Europe and in Turkey. The steepest decline occurred in Western Europe (EAPC = -4.99; 95 % CI: -5.17 to -4.82), whereas Eastern Europe retained the highest residual burden. Turkey ranked mid-range in 2021 yet is projected to experience a 66 % drop in ASMR to 8.9 per 100 000 by 2030, consistent with the UN Sustainable Development Goal 3.4 target for premature mortality reduction. By contrast, Eastern Europe is expected to see its ASMR almost double over the same period. The rate of decline was higher in women than in men. APC analysis showed marked cohort improvements in Western Europe but only limited gains among younger cohorts in Turkey. Country-level 2021 estimates range from the highest ASMR in North Macedonia to the lowest in Switzerland.
Conclusion: Although HSBP-related IS mortality generally decreased across Europe, substantial regional and sex-based disparities persisted. Turkey’s projected gains should be consolidated by sustained salt-reduction and hypertension-control programs, while Eastern Europe requires intensified risk-factor management and stroke care strengthening. The findings must be interpreted cautiously, given the data quality and projection uncertainties.