title: Serum bilirubin and risk of respiratory disease and death.
abstract: BACKGROUND
  Serum total bilirubin levels in healthy patients reflect genetic and environmental factors that could influence the risk of developing respiratory disease.
  
  
  OBJECTIVE
  To examine the relationship between bilirubin levels and respiratory disease.
  
  
  METHODS
  Cohort study among 504,206 adults from a UK primary care research database (the Health Improvement Network) with serum bilirubin levels recorded but no evidence of hepatobiliary or hemolytic disease. Data were recorded between January 1988 and December 2008.
  
  
  METHODS
  Incidence of chronic obstructive pulmonary disease (COPD), lung cancer, and all-cause mortality.
  
  
  RESULTS
  Median bilirubin levels were 0.64 mg/dL (interquartile range, 0.47-0.88 mg/dL) in men and 0.53 mg/dL (interquartile range, 0.41-0.70 mg/dL) in women. There were 1341 cases of lung cancer, 5863 cases of COPD, and 23,103 deaths, with incidence rates of 2.5, 11.9, and 42.5 per 10,000 person-years, respectively. The incidence of lung cancer per 10,000 person-years in men was 5.0 (95% confidence interval [CI], 4.2-6.0) in the first decile category of bilirubin compared with 3.0 (95% CI, 2.3-3.8) in the fifth decile. The corresponding incidences for COPD in men were 19.5 (95% CI,17.7-21.4) and 14.4 (95% CI, 12.7-16.2). The mortality rates per 10,000 person-years in men were 51.3 (95% CI, 48.5-54.2) in the first decile category compared with 38.1 (95% CI, 35.5-40.8) in the fifth decile. The associations were similar for women. After adjusting for other important health indicators, regression estimates for incidence rate of lung cancer per 0.1-mg/dL increase in bilirubin level were an 8% decrease (95% CI, 5%-11%) for men and an 11% decrease (95% CI, 7%-14%) for women. The regression estimate for COPD in men per 0.1-mg/dL increase in bilirubin level was a 6% decrease (95% CI, 5%-7%) and for mortality in men was a 3% decrease (95% CI, 2%-3%) after accounting for other health indicators. The results for COPD and mortality in women were very similar.
  
  
  CONCLUSIONS
  Among patients with normal-range bilirubin levels in primary care practices, relatively higher levels of bilirubin were associated with a lower risk of respiratory disease and all-cause mortality.
authors.affiliation: Research Department of Primary Care and Population Health, University College London, Royal Free Hospital, Rowland Hill Street, London NW3 2PF, England. laura.horsfall@ucl.ac.uk
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Horsfall
authors.forename: Greta
authors.initials: G
authors.lastname: Rait
authors.forename: Kate
authors.initials: K
authors.lastname: Walters
authors.forename: Dallas M
authors.initials: DM
authors.lastname: Swallow
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Pereira
authors.forename: Irwin
authors.initials: I
authors.lastname: Nazareth
authors.forename: Irene
authors.initials: I
authors.lastname: Petersen
mesh_terms: D000328:Adult; D000368:Aged; D001663:Bilirubin / Q000097:blood*; D015415:Biomarkers / Q000097:blood*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008175:Lung Neoplasms / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D009026:Mortality; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology*; D012306:Risk; D006113:United Kingdom / Q000453:epidemiology; D055815:Young Adult
chemical_list: D015415:Biomarkers; D001663:Bilirubin