Ambient temperature and spontaneous intracerebral haemorrhage: a cross-sectional analysis in Tainan, Taiwan

OBJECTIVES Ambient temperature has been reported to play a role in the occurrence of spontaneous intracerebral haemorrhage (ICH). This study aimed to investigate the relation between ambient temperature of onset time and ICH and the effect of hourly temperature within 72 h before ICH. DESIGN This is a cross-sectional case-only study and a retrospective analysis of a prospective database. SETTING Two medical centres in Southern Taiwan participating a prospective stroke registry. PARTICIPANTS A total of 933 patients with ICH registered from August 2006 to July 2008. PRIMARY AND SECONDARY OUTCOME MEASURES The hourly temperature was collected, and patients were grouped according to the deciles of hourly temperature at onset. Primary outcome was the association between the number of ICH cases and mean temperature (or temperature variation). Secondary outcome was the difference of onset temperature and hourly temperature before onset in patients with known onset time. RESULTS Winter (n=282) had significant higher ICH cases than other seasons (n=651; p=0.002). Of those patients with an exact time of onset, the results showed 13% patients occurred at the lowest decile temperature group (<17.4°C) and 8% patients occurred at the highest decile temperature group (>30.8°C). It showed a significant temperature change before onset for these patients (p<0.005). CONCLUSIONS This study showed that lower ambient temperature and variation of temperatures precipitated ICH in southern Taiwan. Better protecting vulnerable people from cold temperatures may prevent the occurrences of ICH.