Incidence of stroke and season of the year: evidence of an association.
Evidence of seasonal variation in the incidence of stroke is inconsistent. This may be a likely consequence of one or more methodological shortcomings of the studies investigating this issue, including inappropriate analytic models, insufficient length of time, small sample size, and a regional (vs. national) focus. The authors' objective was to ascertain whether an association exists between season of the year and the incidence of stroke by using a methodological approach designed to overcome these limitations. The authors used a longitudinal study design involving 72,779 veterans hospitalized for stroke at any Veterans Affairs hospital nationally during the years 1986-1995. These data were analyzed by using time series methods. There was clear evidence of a seasonal occurrence for stroke in general. This seasonal effect was found for ischemic stroke, but not for hemorrhagic stroke. The peak occurrence was in mid-May. Neither the region (i.e., climate) nor the race of the patient substantially modified the seasonal trend. An explanation for this pattern remains to be determined.
Oberg
A L
AL
Department of Statistics, North Carolina State University, Raleigh, USA.
Ferguson
J A
JA
McIntyre
L M
LM
Horner
R D
RD
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044383:Black People; D002980:Climate; D015331:Cohort Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D012307:Risk Factors; D012621:Seasons; D020521:Stroke / Q000453:epidemiology*; D014481:United States / Q000453:epidemiology; D044465:White People; D001741:Black or African American