Circadian and seasonal rhythms of acute upper gastrointestinal bleeding in Beijing.

OBJECTIVE To investigate the circadian and seasonal patterns in the presentation of acute upper gastrointestinal bleeding (AUGIB) in Beijing, China. METHODS Medical records of the Beijing Emergency Medical Service System (EMSS) for 1 August 2005 to 31 July 2007 were reviewed; all patients diagnosed with AUGIB were included in the study. RESULTS 2580 patients were recorded in the EMSS system with a diagnosis of AUGIB during the study period. 1888 (73%) were male and 692 (27%) were female. Mean age was 53+/-20 years for male patients and 63+/-21 years for female patients. Significant differences in the presentation of AUGIB were noticed between seasons (p<0.001) and months (p<0.001). The number of cases in cold months (from December to April) was significantly higher than that in warm months (June to September). There was a significant circadian rhythm; there were fewer cases during daytime hours compared with night-time hours (p<0.001). CONCLUSIONS The presentation of AUGIB in Beijing has a clear seasonal and circadian rhythm. Circadian and seasonal rhythms associated with AUGIB may aid in identifying modifiable risk factors in individuals and populations.