Outcomes for patients with ischaemic stroke and atrial fibrillation: the PRISM study (A Program of Research Informing Stroke Management)

Abstract

Background: In the past decade the prevalence of atrial fibrillation (AF) has been increasing in ageing populations while stroke prevention and management have advanced. To inform clinician practice, health service planning and further research, it is timely to reassess the burden of AF-related ischaemic stroke.

Methods: We identified patients aged 18+ years with a primary or stay diagnosis of ischaemic stroke (ICD-10-AM I63.x), from July 1, 2000 to June 30, 2006, using an administrative health dataset of all hospitalisations in New South Wales (population ∼7 million). Fact of death was determined to December 2007.

Results: Of the 26,960 index cases of ischaemic stroke, 25.4% had AF recorded during admission. Median age for AF and non-AF patients was 80.4 and 75.2 years, respectively (p < 0.001). Mortality was significantly higher in patients with AF at 30 days (19.4 vs. 11.5%), 90 days (27.7 vs. 15.8%) and 365 days (38.5 vs. 22.6%) (p values <0.0001). Adjusting for age and co-morbidities reduced these differences, with 90-day mortality of 20.9% in AF patients versus 14.7% in non-AF patients (p value <0.0001). The effect of AF on outcomes appears stronger in younger stroke patients relative to patients without AF (p value(interaction) <0.0001). At 30 days, the relative risk of mortality due to AF was 3.16 (95% CI 1.92-5.25) amongst those younger than 50, 1.71 (95% CI 1.32-2.22) in patients aged 50-64 years, 1.39 (95% CI 1.16-1.66) in patients aged 65-74 years, 1.29 (95% CI 1.17-1.43) in those aged 75-84 years, and 1.23 (95% CI 1.13-1.33) in those aged 85+ years. AF patients, surviving admission, spent a median of 19.2 days (95% CI 18.4-20.1) in hospital compared with 14.5 days (95% CI 13.9-15.1) for patients without AF (p < 0.001), with differences in length of stay greatest in younger patients (p value(interaction) <0.0001). 90-Day stroke survivors with AF spent an average of 21.5 days (95% CI 20.6-22.4) in hospital versus 16.6 days (95% CI 15.9-17.2) in those without AF. AF patients accessed more in-hospital rehabilitation (36.6%; 95% CI 35.0-38.2) than patients without AF (31.8%; 95% CI 31.0-32.7) (p value <0.0001), and differences in the proportion of AF versus non-AF patients accessing rehabilitation was greatest in younger patients (p value(interaction) <0.0006).

Conclusions: Ischaemic stroke patients with AF have substantially worse outcomes than patients without AF, which can be partly explained by older age and greater co-morbidities. We have quantified the large effect of AF in younger patients and our results strongly argue for new antithrombotic research in young AF patients.