Temporal and Age-Specific Trends in Acute Stroke Incidence: A 15-Year Population-Based Study of Administrative Data in Ontario, Canada.

BACKGROUND

Contemporary data on temporal trends in acute stroke incidence, specific to stroke type and age, are lacking. We sought to evaluate temporal trends in incidence of ischemic stroke and intracerebral hemorrhage over 15 years in a large population.

METHODS

We used linked administrative data to identify all emergency department visits and hospital admissions for first-ever ischemic stroke or intracerebral hemorrhage in Ontario, Canada from 2003-2017. We evaluated annual age-/sex-standardized incidence per 100,000 person-years for ischemic stroke and intracerebral hemorrhage across the study period. We used negative binomial regression to determine incidence rate ratios for each year compared to 2003, with assessment of modification by age, sex, or stroke type.

RESULTS

Our cohort had 163,574 people with stroke (88% ischemic stroke). For ischemic stroke and intracerebral hemorrhage combined, age-/sex-standardized incidence decreased between 2003 and 2011 (standardized rate 109.4 to 85.8 per 100,000; 22%), then increased until 2017 (standardized rate 96.8 per 100,000; 13%). The pattern of change was similar for ischemic stroke and intracerebral hemorrhage, and for men and women, but was modified by age. For those aged 60 and above, adjusted incidence rate ratios decreased from 2003 to 2011 then subsequently increased, whereas for those aged <60 years incidence rate ratios increased throughout the entire study time period, particularly after 2011.

CONCLUSIONS

Acute stroke incidence decreased from 2003 to 2011 but subsequently increased until 2017. Among those aged <60, incidence increased continuously from 2003 to 2017 but especially after 2011. The underlying reasons for these changes should be determined.