Temporal trends in incidence, recurrence and prevalence of stroke in an era of ageing populations, a longitudinal study of the total Swedish population

Abstract

Background: Stroke incidence has declined during the past decades. Yet, there is a concern that an ageing population together with improved survival after stroke will result in a raised proportion of the population who have experienced a stroke, as well as increasing incidence rate of recurrent strokes, and, absolute numbers of strokes. The objectives of this study were to investigate how the age specific incidence rates of recurrent strokes have developed in relation to the incidence rates of first strokes and how the postponement in age look like, and to see how the prevalence proportion of stroke as well as the absolute number of incident strokes has changed over time.

Methods: This study includes the total Swedish population born 1890-1954 living in Sweden from 1987. Stroke was identified through hospital admissions and deaths in national health registers (mandatory for all hospitals in Sweden). Age specific incidence rates were calculated for first, second, all recurrent, and all strokes for each calendar year between 1994 and 2014 for each age between 60 and 104 years. The proportion in the population with a history of stroke up to 7 years back in time was also calculated for different age groups and for different calendar years.

Results: Not only the incidence rate of first stroke but also of recurrent strokes have declined. The declines are evident in all ages up to 90 years of age, but not in ages above 90 years. Despite improved survival in stroke, the prevalence proportion has declined over the period and was around 3% in 2014 (somewhat higher for men than women). Even incident cases of stroke in absolute number has declined.

Conclusions: Decreasing incidence rates of stroke have offset an increase in both absolute and relative numbers of stroke that otherwise would have taken place due to improved survival and an ageing population. The decline in stroke recurrence has been as strong as the decline in first strokes.

Trial registration: ClinicalTrials.gov NCT02123641.

Conflict of interest statement

Ethics approval and consent to participate

An ethics approval for this study was obtained from the Regional Ethics Committee in Stockholm (Regionala Etikprövningsnämnden), Dnr. 2011/136–31/5.

Consent for publication

Not applicable

Competing interests

The authors declare that they have no competing interests.

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Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Figures

Fig. 1

Incidence rate of first and all strokes (values on left Y-axis) and incidence rate of second and all recurrent strokes (values on right Y-axis). Values presented over the period 1994 to 2014 for men and women aged 60–104 (age adjusted)

Fig. 2

Incidence rate of first stroke (y-axis) and second stroke (x-axis) for men and women aged 60–104 (age adjusted), and correlation coefficients, between 1994 and 2014

Fig. 3

a Age distribution of first and second stroke 1994–2014. Men and women. b Mean age of first and second stroke over the period 1994 to 2014. Men and women

Fig. 4

Proportion of the population alive 31st of December 2014 with a history of stroke up to 7 years back in time, for different age groups. Men and women

Fig. 5

Proportion of the population alive 31st of December with a history of stroke up to 7 years back in time, for 5 different calendar years, ages 60 to 104 years. Men and women