Seasonal variation in stroke in the Hunter Region, Australia: a 5-year hospital-based study, 1995-2000.
OBJECTIVE
Seasonal variation in stroke has long been recognized. To date, there are minimal published data on seasonal variations in rates of stroke and subsequent case fatality in the Southern Hemisphere. The aim of this study was to examine stroke seasonality through the use of data from a hospital-based stroke register in the Hunter Region of New South Wales, Australia.


METHODS
From July 1, 1995, to June 30, 2000, 3803 stroke events were registered in residents of the Hunter Region, New South Wales, Australia. We analyzed the trend of seasonal and monthly stroke attack rates and case-fatality rates using Poisson regressions with age and sex as covariates.


RESULTS
Stroke attack rates were highest in the winter and lowest in the summer. From February (summer) to July (winter), there was a significant trend in increasing stroke attack rates (rate ratio, 1.07; 95% confidence interval, 1.05 to 1.10; P<0.001). This increase was seen mainly in those >or=65 years of age. Case-fatality rates showed similar trends with a 1- to 2-month lag compared with attack rates.


CONCLUSIONS
There is an increase in stroke attack rates and case-fatality rate from summer to winter in the Hunter Region, Australia. These trends are similar to those found in the Northern Hemisphere.
Wang
Yang
Y
John Hunter Hospital/Hunter Medical Research Institute, New Lambton Heights, Australia. Yang.Wang@hunter.health.nsw.gov.au
Levi
Christopher R
CR
Attia
John R
JR
D'Este
Catherine A
CA
Spratt
Neil
N
Fisher
Janet
J
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002543:Cerebral Hemorrhage / Q000453:epidemiology* / Q000401:mortality; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D038801:International Classification of Diseases; D008297:Male; D008875:Middle Aged; D009517:New South Wales / Q000453:epidemiology; D016012:Poisson Distribution; D012042:Registries / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012621:Seasons; D012737:Sex Factors; D020521:Stroke / Q000453:epidemiology* / Q000401:mortality; D013345:Subarachnoid Hemorrhage / Q000453:epidemiology / Q000401:mortality; D013696:Temperature