title: [Circadian variation of the incidence of upper gastrointestinal bleeding and its relationship with climatic factors].
abstract: OBJECTIVE
  To study the circadian patterns of the incidence of upper gastrointestinal bleeding (UGIB) and its relationship with climatic factors in Beijing.
  
  
  METHODS
  We searched all UGIB records from August 1, 2005 to July 31, 2007 from Beijing Emergency Center and tracked the meteorological data during the same period. The variation of the incidence of UGIB was compared based on day, month, and season. The relation between climatic factors and the incidence of UGIB was also analyzed.
  
  
  RESULTS
  Totally 2 580 patients, including 1 888 males (73.2%) and 692 females (26.8%) were included in the study. The mean age was significantly different between males and females [(53.3 +/- 20.4) years vs. (63.3 +/- 20.7) years, P < 0.05]. The occurrence of UGIB were significantly different among different seasons (chi2 = 49.82, P < 0.01), months (chi2 = 83.43, P < 0.01), and hours (chi2 = 126.79, P < 0.01). UGIB cases were presented more frequently in winter and spring, especially in January. More UGIB cases were presented at night, especially from 8 pm to midnight. Partial correlation test showed that the incidence of UGIB significantly correlated with temperature (r = -0.3785, P = 0.001) and barametric pressure (r = -0.3002, P = 0.011). No correlation was found between UGIB incidence and wind speed (P = 0.086) and relative humidity (P = 0.971).
  
  
  CONCLUSIONS
  The incidence of UGIB varies in different months and seasons in Beijing. Its climate-related risk factors may include temperature and barametric pressure, but not include relative humidity and wind speed.
authors.affiliation: Department of Emergency, PUMC Hospital, CAMS and PUMC, Beijing 100730, China.
authors.forename: Tie-Kuan
authors.initials: TK
authors.lastname: Du
authors.forename: Hou-Li
authors.initials: HL
authors.lastname: Wang
authors.forename: Teng-Da
authors.initials: TD
authors.lastname: Xu
authors.forename: Xu
authors.initials: X
authors.lastname: Ji
authors.forename: Yan-Ping
authors.initials: YP
authors.lastname: Zhang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002681:China / Q000453:epidemiology; D002940:Circadian Rhythm; D005260:Female; D006471:Gastrointestinal Hemorrhage / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D008297:Male; D008685:Meteorological Concepts; D008875:Middle Aged; D012621:Seasons