Diurnal variation in onset of hemorrhagic stroke is independent of risk factor status: Takashima Stroke Registry.
BACKGROUND
We examined the circadian periodicity of hemorrhagic stroke onset to identify any existing specific pattern and its relationship with conventional stroke risk factors using 14-year stroke registration data.


METHODS
Data were obtained from the Takashima Stroke Registry, which covers a stable population of approx. 55,000 in Takashima County in central Japan. Out of 499 registered first-ever hemorrhagic stroke events during 1990-2003, there were 429 (186 men, 243 women) events with classifiable onset time. Hemorrhagic stroke incidence was categorized as occurring at night (midnight to 6 a.m.), morning (6 a.m. to noon), afternoon (noon to 6 p.m.) or evening (6 p.m. to midnight). The OR (with 95% CI) of having a stroke in the morning, afternoon or evening were calculated, with night serving as reference.


RESULTS
There was significant diurnal variation in hemorrhagic stroke incidence (p < 0.001). The proportion of hemorrhagic strokes was highest in the morning (36.1%, 95% CI: 31.7-40.8) and lowest in the night (11.9%, 95% CI: 9.1-15.3). An excess stroke incidence in the morning was observed in both genders, in subjects < 65 years and > or =65 years, and in both intracerebral hemorrhage and subarachnoid hemorrhage. A second surge was also observed during the later part of the day. The higher daytime risk persisted after adjusting for age, gender, and risk factors.


CONCLUSIONS
In the examination of circadian variation of hemorrhagic stroke onset, a 2-peak temporal distribution was observed, which was independent of conventional risk factors.
Turin
Tanvir Chowdhury
TC
Department of Health Science, Shiga University of Medical Science, Shiga, Japan. turin@belle.shiga-med.ac.jp
Kita
Yoshikuni
Y
Rumana
Nahid
N
Takashima
Naoyuki
N
Ichikawa
Masaharu
M
Sugihara
Hideki
H
Morita
Yutaka
Y
Hirose
Kunihiko
K
Murakami
Yoshitaka
Y
Miura
Katsuyuki
K
Okayama
Akira
A
Nakamura
Yasuyuki
Y
Abbott
Robert D
RD
Ueshima
Hirotsugu
H
D000367:Age Factors; D000368:Aged; D005260:Female; D006801:Humans; D015994:Incidence; D020300:Intracranial Hemorrhages / Q000453:epidemiology* / Q000401:mortality; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D017440:Photoperiod; D012042:Registries; D012307:Risk Factors; D012737:Sex Factors; D020521:Stroke / Q000453:epidemiology* / Q000401:mortality; D013345:Subarachnoid Hemorrhage / Q000453:epidemiology / Q000401:mortality; D013997:Time Factors