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Temporal trends in stroke admissions in Denmark 1997–2009
BMC Neurology
Temporal trends in stroke admissions in Denmark 1997-2009
Malene Nhr Demant 0
Charlotte Andersson 0
Ole Ahlehoff 0
Mette Charlot 0
Jonas Bjerring Olesen 0
Anne Gjesing 0
Peter R Hansen 0
Gunnar H Gislason 0
Thomas Truelsen 2
Christian Torp-Pedersen 1
0 Department of Cardiology, Copenhagen University Hospital Gentofte , Niels Andersens Vej 65, 2900 Hellerup , Denmark
1 Department of Cardiology, Aalborg University, Aalborg Hospital , Aalborg , Denmark
2 Department of Neurology, Herlev University Hospital , Herlev Ringvej 75, 2730 Herlev , Denmark
Background: The Stroke burden is increasing in many populations where health institutions may experience more patients. We wanted to examine whether incidence rates and absolute number of hospitalized stroke patients remained stable in Denmark during a 13 years period where exposure to major stroke risk factors decreased, changes in stroke treatment was implemented, and the age of the population increased. Methods: The Danish National Patient Register was used to identify all subjects 25 years of age or above admitted with a first time stroke in Denmark from 1997-2009. Incidence rates (IRs) and age-adjusted Poisson regression analyses were used to examine trends in age-, gender- and stroke subtype (ischaemic or unspecified). Results: During the 13-year observation period there were 53.5 million person-years at risk (PY) and a total of 84,626 male and 84,705 female stroke patients were admitted to Danish hospitals. The IRs of hospitalized strokes per 1000 PY was 3.21 (95% confidence interval [CI] 3.16-3.27) in 1997, 3.85 (95% CI 3.79-3.91) in 2003 and 3.22 (95% CI 3.16-3.28) in 2009, respectively. Incidence rate ratios of hospitalized stroke events adjusted for age in the period 2007-2009 compared to 1997-2000 were 0.89 (95% CI 0.87- 0.91) for men and 0.92 (95% CI 0.90-0.94) for women. The incidence of hospitalized unspecified strokes decreased from 1997 to 2009 whereas there was a steep rise in incidence for hospitalization with specified ischemic stroke during this period. Conclusion: This study found a constant rate of stroke hospitalization in Denmark from 1997-2009. The overall rate of hospitalized strokes adjusted for age decreased during this period.
Stroke; Temporal trends; Epidemiology
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Background
Stroke is a leading cause of death and acquired adult
disability and it is estimated that globally each year 5.8
million people die from stroke [1]. In high income
countries it has been stated that approximately 1 in 20
adults is affected by stroke and the incidence of acute
cerebrovascular events (strokes and transient ischemic
attack combined) exceeds the incidence of acute coronary
heart disease [2]. In the recent INTERSTROKE study
five risk factors including hypertension, current smoking,
abdominal obesity, diet and physical activity, were
associated with 80% of the global risk of stroke and
interventions to reduce these factors are therefore likely to
reduce the stroke incidence [3]. The observation period in
this study covers a time period where smoking prevalence
among Danes in general declined and treatment of
hypertension and hypercholesterolemia gradually improved
[4,5]. During the same period life expectancy and mean
age of the population increased which could be followed
by a higher absolute number of stroke events. Increasing
life expectancy and mean age of the population would
therefore be likely to increase the absolute number of
stroke events. Different trends in stroke incidence have
been reported worldwide, and it is currently not known
if the stroke incidence has changed in Denmark [6-9].
Temporal changes in admission and diagnostic practices
may tend to increase the overall hospitalization rates,
which is a burden to health facilities even if it does not
reflect an actual increase in stroke incidence rates.
Therefore the aim of this study was to examine temporal
trends in stroke admissions in Denmark in the period
19972009.
Methods
Data sources
All Danish residents have a unique civil registration
number in the Danish Civil Registration System that
enables individual level-linkage between nationwide
registries. This study was based on The Danish National
Patient Registry which registers all hospital discharge
diagnoses since 1978. At discharge all admissions are
registered by one primary and if appropriate one or
more secondary diagnoses according to the International
Classification of Disease, the 8th revision (ICD-8) from
1978 to 1994 and the 10th revision (ICD-10) from 1994.
Population and demographics
The population demographics used in Table 1 was based
on a stroke population and a control population that
included all Danish citizens who were alive and older
than 25 years as of January 1st 1997. The stroke population
included individuals registered with a first diagnosis
of stroke during the period from January 1st 1997 to
December 31st 2009 and the control population
included individuals with no stroke diagnosis dur (...truncated)