Diverging Trends in the Incidence of Spontaneous Intracerebral Hemorrhage in Sweden 2010-2019: An Observational Study from the Swedish Stroke Register (Riksstroke).

ABSTRACT

INTRODUCTION: Although ischemic stroke incidence has decreased in Sweden over the past decade, trends in spontaneous intracerebral hemorrhage (ICH) incidence are less well delineated. In this time period, there has been a dramatic increase in use of oral anticoagulants (OAC). The aim of our study was to investigate incidence trends in spontaneous first-ever ICH in Sweden between 2010 and 2019, with a focus on non-OAC-associated and OAC-associated ICH. METHODS: We included patients (≥18 years) with first-ever ICH registered in the hospital-based Swedish Stroke Register (Riksstroke) 2010-2019. Data were stratified by non-OAC and OAC ICH and analyzed for 2010-2012, 2013-2016, and 2017-2019. Incidence rates are shown as crude and age-specific per 100,000 person-years. RESULTS: Between 2010 and 2019, 22,289 patients with first-ever ICH were registered; 18,325 (82.2%) patients with non-OAC ICH and 3,964 (17.8%) patients with OAC ICH. Annual crude incidence (per 100,000) of all first-ever ICH decreased by 10% from 29.5 (95% CI 28.8-30.3) to 26.7 (95% CI 26.0-27.3) between 2010-2012 and 2017-2019. The crude incidence rate of non-OAC ICH decreased by 20% from 25.7 (95% CI 25.0-26.3) to 20.7 (95% CI 20.1-21.2), whereas OAC ICH increased by 56% from 3.86 (95% CI 3.61-4.12) to 6.01 (95% CI 5.70-6.32). The proportion of OAC ICH of all first-ever ICH increased between 2010-2012 and 2017-2019 from 13.1% to 22.5% (p < 0.001). Proportional changes were largest in the age group ≥85 years with a decrease in non-OAC ICH by 32% from 155 (95% CI 146-164) to 106 (95% CI 98.6-113) and an increase in OAC ICH by 155% from 25.7 (95% CI 22.1-29.4) to 65.5 (95% CI 59.9-71.2). CONCLUSION: Incidence of first-ever ICH in Sweden decreased by 10% between 2010 and 2019. We found diverging trends with a 20% decrease in non-OAC-associated ICH and a 56% increase in OAC-associated ICH. Further research on ICH epidemiology, analyzing non-OAC and OAC-associated ICH separately, is needed to follow up these diverging trends including underlying risk factors.