Outcome of Stroke Prevention : Analyses Based on Data from Riks-Stroke and Other Swedish National Registers
Abstract: The aim of this thesis was to explore variations in stroke prevention and the effect of prevention on outcome. The studies were based on patients registered in the Swedish Stroke Register between 2001 and 2009 and although used to different extents in each paper, additional information was retrieved through linkage to The National Patient Register, the Cause of Death Register, the Prescribed Drug Register and the Total Population Register.Cardiovascular risk factors were prevalent among ischemic stroke (IS) patients; however, they were not always prescribed the drugs recommended, and increasing age was an important negative predictor (Paper I).After IS, the rate of hemorrhage in patients prescribed antiplatelet agents (2.4 per 100 person-years) was double to results from randomized controlled trails, but was similar for patients prescribed warfarin (2.5 per 100 person-years). Age ≥75 years and previous hemorrhage were associated with a moderately increased risk of future hemorrhage (Paper II).Among IS patients with atrial fibrillation, one-third was prescribed warfarin and two-thirds were prescribed antiplatelets. After adjustment for a propensity score (used to adjust for the non-randomized design), warfarin was associated with a reduced risk of death (0.67; 95% CI, 0.63-0.71) (Paper III). The rate of subsequent hemorrhagic stroke was 0.4 per 100 person-years and the risk did not change (HR 1.04; 95% CI, 0.73-1.48) when later years of the 2000s (inclusion period 2005-8: follow-up until 2009) was compared with earlier years (inclusion period 2001-4: follow-up until 2005) (Paper IV, cohort).Although the risk of first-ever hemorrhagic stroke more than doubled with warfarin than without, the risk did not change between 2006 and 2009 (Paper IV, case-control).In summary, the prescription of secondary preventive drugs varies with age, even though cardiovascular risk factors are prevalent in all ages. The risk of death and hemorrhage are affected by the type of antithrombotic prescribed. Therefore, it is important individual’s stroke and bleeding risks in stroke prevention are assessed.
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