OBJECTIVES Equitable and timely access to health care for all patients, regardless of patient characteristics is one of the main policy targets in European health systems. Many studies show that the risk of mortality after admission to a hospital following acute diseases is significantly higher on weekends than on weekdays. This weekend effect is well documented, however reasons are still discussed controversially. In Austria, evidence for variation of health outcomes overnight, at holidays or at the weekend is scarce. This study aims to explain weekend effects in inpatient care for acute stroke in Austrian acute care hospitals.

Methods
The study analyses secondary datasets from public acute care hospitals in Austria in 2014 (Austrian DRG Data). The study cohort includes all adult patients suffering from acute ischaemic stroke admitted to public Austrian acute care hospitals (approx. 20,000 patients in 130 hospitals). Data sources contain patient characteristics and quality indicators that can be derived from DRG data (e.g. re-hospitalisations). We apply multivariate regression analysis controlling for patient-level as well as hospital characteristics. The primary outcome variable is case fatality rate within 30 days after admission and the primary independent variable is admission on weekends (Saturday, Sunday, and holidays) versus weekdays. RESULTS:
The number of admissions following stroke are significantly lower on weekends than on weekdays. At the same time, the risk to die after an admission at a weekend is significantly higher. Patient characteristics on weekends differ with regard to patient demographics, which may indicate different severity of cases. First results do not indicate a clear weekend effect regarding mortality.

DISCUSSION
Patients admitted to Austrian acute care hospitals following stroke show a higher mortality than patients admitted on weekdays. Disparities in patient characteristics may explain observed differences in weekend mortality. The findings should initiate further research and critical evaluation whether resources, expertise and staff should be provided for critical care in the same quantity and quality throughout the week. Further analysis and rigorous risk adjustment is needed to show clearer evidence.