title: Low air temperature increases the risk of oesophageal variceal bleeding: a population and hospital-based case-crossover study in Taiwan.
abstract: Studies concerning seasonal variations and the impact of air temperature on oesophageal variceal bleeding have yielded conflicting results. We aimed to explore the impact of air temperature on the occurrence of variceal bleeding.
  
  
  
  A case-crossover study design was employed, and two cohorts were used, including the NHI-EVB cohort from the National Health Insurance Research Database of Taiwan from 1 January 1999 to 31 December 2010, and the VGH-EVB cohort from the Taipei Veterans General Hospital, from 4 May 2002 to 31 December 2010. A conditional logistic regression model was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).
  
  
  
  In total, 2542 cases from the NHI-EVB cohort and 220 cases from the VGH-EVB cohort were analysed. Our analysis showed that low air temperature (LAT) increased the risk of variceal bleeding regardless of age, sex, decompensated cirrhosis, Child-Pugh classification, aetiology of liver disease and concomitant hepatocellular carcinoma; the lag effect was also observed. The ORs per 5°C decrease in daily mean air temperature were 1.144 (95% CI, 1.060-1.235) for the NHI-EVB cohort and 1.307 (95% CI: 1.031-1.658) for the VGH-EVB cohort. Oesophageal variceal bleeding in patients with small varices, end-stage liver disease score ≧15 or those using non-selective beta blockers was not influenced by air temperature.
  
  
  
  Patients have higher risk of oesophageal variceal bleeding at low air temperature regardless of age, sex, aetiology of cirrhosis, Child-Pugh classification, decompensated cirrhosis and concomitant hepatocellular carcinoma and can be protected by use non-selective beta blockers.
authors.affiliation: Division of Gastroenterology, Department of Medicine, Taipei City Hospital Renai Branch, Taipei, Taiwan.|School of Medicine, National Yang-Ming University School, Taipei, Taiwan.
authors.forename: Wen-Chieh
authors.initials: WC
authors.lastname: Wu
authors.affiliation: School of Medicine, National Yang-Ming University School, Taipei, Taiwan.|Division of Nephrology, Department of Medicine, Taipei City Hospital Heping Fuyou Branch, Taipei, Taiwan.
authors.forename: Yung-Tai
authors.initials: YT
authors.lastname: Chen
authors.affiliation: School of Medicine, National Yang-Ming University School, Taipei, Taiwan.|Endoscopy Center for Diagnosis and Treatment, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Ping-Hsien
authors.initials: PH
authors.lastname: Chen
authors.affiliation: School of Medicine, National Yang-Ming University School, Taipei, Taiwan.|Division of Gastroenterology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.|Institute of Clinical Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Chien-Wei
authors.initials: CW
authors.lastname: Su
authors.affiliation: Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Wei-Ming
authors.initials: WM
authors.lastname: Huang
authors.affiliation: Endoscopy Center for Diagnosis and Treatment, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Tsung-Chieh
authors.initials: TC
authors.lastname: Yang
authors.affiliation: Institute of Clinical Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan.|Division of Nephrology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Szu-Yuan
authors.initials: SY
authors.lastname: Li
authors.affiliation: Department of Family Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.|Department of Family Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Tzeng-Ji
authors.initials: TJ
authors.lastname: Chen
authors.affiliation: School of Medicine, National Yang-Ming University School, Taipei, Taiwan.|Division of Gastroenterology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Han-Chieh
authors.initials: HC
authors.lastname: Lin
authors.affiliation: School of Medicine, National Yang-Ming University School, Taipei, Taiwan.|Division of Gastroenterology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Fa-Yauh
authors.initials: FY
authors.lastname: Lee
authors.affiliation: School of Medicine, National Yang-Ming University School, Taipei, Taiwan.|Endoscopy Center for Diagnosis and Treatment, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Ming-Chih
authors.initials: MC
authors.lastname: Hou
mesh_terms: D000328:Adult; D000368:Aged; D003080:Cold Temperature / Q000009:adverse effects*; D018592:Cross-Over Studies; D004932:Esophageal and Gastric Varices / Q000453:epidemiology*; D005260:Female; D006471:Gastrointestinal Hemorrhage / Q000453:epidemiology*; D006801:Humans; D008103:Liver Cirrhosis / Q000150:complications*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012307:Risk Factors; D012621:Seasons; D012720:Severity of Illness Index; D013624:Taiwan / Q000453:epidemiology
keywords: air temperature; cirrhosis; meteorology; seasonal pattern; variceal bleeding