Conrad Drescher- Institutionen för kliniska vetenskaper, Lund

Title: Stroke epidemiology in Sweden 2010-2019 - Trends in incidence, prognosis and health economics based on the Swedish Stroke Register (Riksstroke)

Main supervisor: Jesper Petersson

Reviewers: Professor Johan Zelano (Göteborg) and Professor Gunnar Engström (Lund)

Abstract

Background

Stroke is a leading cause of death and disability worldwide. Stroke incidence and mortality rates appear to have decreased over the last decades in Sweden. Likely causes are improvements in primary and secondary prevention as well as improved stroke care. However, there is a limited number of epidemiological studies on temporal trends in stroke in Sweden after 2010. Within this period there have been considerable advances in acute treatment of stroke, such as endovascular interventions (thrombectomy), and in primary/secondary prevention in patients with atrial fibrillation with novel oral anticoagulants (NOAC). 

Research questions

Based on data from the Swedish Stroke Register (Riksstroke) from 2010 to 2019, we want to investigate

• trends in incidence of first-ever and recurrent ischemic stroke (IS) (project 1 - published)
• trends in spontaneous first-ever ICH, with a focus on non-OAC-associated and OAC-associated ICH (project 2 - published)
• trends in case-fatality and functional outcome 90 days after stroke (project 3 - preliminary data)
• the health economic impact of changes in stroke incidence and outcome (project 4 - in planning)

Preliminary results

Project 1:

Incidence in both first-ever and recurrent IS decreased between 2010 and 2019 with a higher proportional decrease in recurrent IS (33%) compared to first-ever IS (17%). Favorable trends were most marked in patients ≥75 years and women. 

Project 2: 

Incidence of first-ever ICH decreased by 10% between 2010 and 2019. Diverging trends were observed with a decrease in non-OAC-associated ICH (-20%) and an increase in OAC-associated ICH (+56%).

Project 3: (preliminary results)

Case-fatality 90 days after stroke decreased from 15.9% to 14.1% between 2010 and 2019 and the proportion of patients with favorable functional outcome (modified Rankin Scale 0-2) increased from 47.7% to 51.1%

Significance

The incidence of ischemic stroke continues to decline in Sweden and our study of a nationwide cohort shows a marked decrease in recurrent IS incidence. This result likely results from improvements in secondary stroke prevention. 

The decline in first-ever ICH incidence may reflect improvements in primary prevention, such as treatment of hypertension. Increasing trends in OAC-associated ICH underlines the need for improvement of acute management of OAC ICH, but also in general prevention of cardiovascular disease.

Published studies

1. Drescher C, Buchwald F, Ullberg T, Pihlsgård M, Norrving B, Petersson J. Epidemiology of First and Recurrent Ischemic Stroke in Sweden 2010–2019: A Riksstroke Study. Neuroepidemiology. 2022; 56(6):433–42.
2. Drescher C, Buchwald F, Ullberg T, Pihlsgård M, Norrving B, Petersson J. Diverging Trends in the Incidence of Spontaneous Intracerebral Hemorrhage in Sweden 2010–2019: An Observational Study from the Swedish Stroke Register (Riksstroke). Neuroepidemiology. 2023; 57(6):367-76.