Temporal trends in stroke admissions in Denmark 1997-2009

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.