Temporal trends in stroke admissions in Denmark 1997–2009

BMC Neurology, Oct 2013

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.

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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 - 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)


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Malene Demant, Charlotte Andersson, Ole Ahlehoff, Mette Charlot, Jonas Olesen, Anne Gjesing, Peter R Hansen, Gunnar H Gislason, Thomas Truelsen, Christian Torp-Pedersen. Temporal trends in stroke admissions in Denmark 1997–2009, BMC Neurology, 2013, pp. 156, 13, DOI: 10.1186/1471-2377-13-156