title: Serum Bilirubin Is Inversely Associated with Increased Arterial Stiffness in Men with Pre-Hypertension but Not Normotension.
abstract: OBJECTIVE
  Serum bilirubin level has shown to be inversely associated with coronary atherosclerosis, and may serve as a protective biomarker of coronary artery disease. Serum bilirubin has also been shown to be negatively associated with brachial-ankle pulse wave velocity (baPWV) in men without a history of hypertension, and in men with hypertension. It is unknown whether such associations can be observed in the pre-hypertensive or normotensive population. This study thus aimed to investigate the relationship between serum bilirubin level and increased arterial stiffness in subjects with pre-hypertension and normotension for both genders.
  
  
  METHODS
  A cross-sectional sample of 3,399 apparently healthy subjects undergoing a medical check-up at National Cheng Kung University Hospital was enrolled between October 2006 and August 2009, after excluding subjects with serum total bilirubin level greater than 20.52 μmol/L. Increased arterial stiffness was defined as baPWV of 1,400 cm/s or higher as the dichotomous variable and bilirubin as the continuous variable.
  
  
  RESULTS
  Based on multiple linear regression analysis, serum bilirubin level was inversely associated with baPWV in non-hypertensive men (β = -0.066, p < 0.001) but not in non-hypertensive women. In addition, the inverse relationship between bilirubin level and baPWV was found statistically significant only in pre-hypertensive men (β = -0.110, p < 0.001). Multiple logistic regression analysis showed that serum bilirubin was inversely associated with increased arterial stiffness in men with pre-hypertension (odds ratio = 0.955, 95% confidence interval = 0.916-0.996, p < 0.05) but not normotension after adjustment for other confounding factors. However, the relationship between total bilirubin level and increased arterial stiffness did not reach statistical significance for female subjects with pre-hypertension and normotension.
  
  
  CONCLUSIONS
  Serum bilirubin is inversely associated with increased arterial stiffness in men with pre-hypertension but not normotension. The association between bilirubin level and arterial stiffness was not found significant in women.
authors.affiliation: Department of Family Medicine, National Cheng Kung University Hospital, Tainan, Taiwan.
authors.forename: Yao-Hsien
authors.initials: YH
authors.lastname: Huang
authors.affiliation: Department of Family Medicine, National Cheng Kung University Hospital, Tainan, Taiwan.|Department of Family Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Yi-Ching
authors.initials: YC
authors.lastname: Yang
authors.affiliation: Department of Family Medicine, National Cheng Kung University Hospital, Tainan, Taiwan.|Department of Family Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Feng-Hwa
authors.initials: FH
authors.lastname: Lu
authors.affiliation: Department of Family Medicine, National Cheng Kung University Hospital, Tainan, Taiwan.|Department of Family Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.|Department of Family Medicine, National Cheng Kung University Hospital Dou-Liou Branch, Yunlin, Taiwan.
authors.forename: Zih-Jie
authors.initials: ZJ
authors.lastname: Sun
authors.affiliation: Department of Family Medicine, National Cheng Kung University Hospital, Tainan, Taiwan.|Department of Family Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Jin-Shang
authors.initials: JS
authors.lastname: Wu
authors.affiliation: Department of Family Medicine, National Cheng Kung University Hospital, Tainan, Taiwan.|Department of Family Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Chih-Jen
authors.initials: CJ
authors.lastname: Chang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D055109:Ankle Brachial Index; D001663:Bilirubin / Q000097:blood*; D001783:Blood Flow Velocity; D001794:Blood Pressure; D003430:Cross-Sectional Studies; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D006973:Hypertension / Q000097:blood; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D058246:Prehypertension / Q000097:blood*; D063177:Pulse Wave Analysis; D012307:Risk Factors; D012737:Sex Factors; D059289:Vascular Stiffness / Q000502:physiology*; D055815:Young Adult
chemical_list: D001663:Bilirubin