Abstract WP385: Seasonal, Circaseptan and Diurnal Variations in Stroke Onset, Severity and Costs: Findings from the Royal Melbourne Hospital Stroke Registry 2004-2011
Introduction: Information on regular variations in the volume and severity of strokes has important implications for planning of emergency services and resource allocation. A number of studies have investigated seasonal, circaseptan and diurnal variations in stroke incidence but little is known about corresponding variations in stroke severity and costs.
Hypotheses: Following results of previous studies, we hypothesized an increase in strokes in winter months, on Mondays, and between 09:00 and 12:00 hours. We also explored associations between stroke onset and stroke severity and in-patient costs.
Methods: Data were analyzed for 4484 consecutive admissions to the Stroke Care Unit at the Royal Melbourne Hospital (Australia) from January 2005 to September 2011. Temporal variations in stroke frequency, severity and costs were assessed using generalized linear modelling. Stroke severity was measured using NIH Stroke Severity (NIHSS) scores.
Results: The mean (SD) age of patients was 70.6 (14.3) years and 56% were males. Ischemic strokes accounted for 62% of admissions, 19% were haemorrhages, and 19% were TIAs. Stroke frequency varied significantly during the day (p<0.001). Contrary to expectation, strokes peaked between 06:00 and 21:00. The daily incidence of strokes differed significantly during the year (p<0.001), being highest in August (2.8/day, 95%CI 2.6,3.1) and lowest in January (2.1/day, 95% CI 1.8,2.3). Weekday was not associated with variations in stroke frequency (p=0.130). NIHSS scores were not associated with weekday (p=0.465) but varied significantly during the year (p=0.012) and day (p=0.011). Most severe strokes occurred in July and at 12:00-15:00, and least severe strokes occurred in December and at 09:00-12:00. Admission costs differed significantly during the year (p=0.039) but not during the week (p=0.469) or day (p=0.099). The highest admission costs were in August ($16053, 95%CI $12586,$19521) and lowest in October ($11256, 95% $9131,$13380).
Conclusions: The frequency of stroke peaks between late morning and early afternoon and is highest in winter. The severity and costs of stroke admissions are also highest during winter. This information can be used in the planning of emergency services and resource allocation.
- © 2012 by American Heart Association, Inc.