title: Environment-wide association study to identify factors associated with hematocrit: evidence from the Guangzhou Biobank Cohort Study.
abstract: In randomized controlled trials reducing high hematocrit (Hct) in patients with polycythemia vera protects against cardiovascular disease (CVD) events, whereas increasing Hct in anemia patients causes CVD events. Hct is influenced by environmental and lifestyle factors. Given limited knowledge concerning the drivers of Hct, we took an agnostic approach to identify drivers of Hct.
  
  
  
  We used an environment-wide association study to identify environmental and lifestyle factors associated with Hct in 20443 older Chinese adults (mean age = 62.7 years) from the Guangzhou Biobank Cohort Study. We evaluated the role of 25 nutrients, 40 environmental contaminants, two metals (only available for 10405 participants), and six lifestyle factors in relation to Hct, adjusted for sex, age, recruitment phase, and socioeconomic position.
  
  
  
  In a mutually adjusted model vitamin A, serum calcium, serum magnesium, and alcohol use were associated with higher Hct, whereas physical activity was associated with lower Hct.
  
  
  
  Despite the difficulty of ascertaining causality, finding both expected (vitamin A and physical inactivity) and novel factors (serum calcium, serum magnesium and alcohol use) strongly associated with Hct illustrates the utility of environment-wide association study to generate hypotheses regarding the potential contribution of modifiable exposures to CVD.
authors: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors: Yi
authors: Y
authors: Zhong
authors: Molecular Epidemiological Research Centre, Guangzhou Number 12 Hospital, Guangzhou, Guangdong, China.
authors: Chaoqiang
authors: C
authors: Jiang
authors: Department of Public Health and Epidemiology, University of Birmingham, Birmingham, UK.
authors: Kar Keung
authors: KK
authors: Cheng
authors: Molecular Epidemiological Research Centre, Guangzhou Number 12 Hospital, Guangzhou, Guangdong, China.
authors: Weisen
authors: W
authors: Zhang
authors: Molecular Epidemiological Research Centre, Guangzhou Number 12 Hospital, Guangzhou, Guangdong, China.
authors: Yali
authors: Y
authors: Jin
authors: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China. Electronic address: hrmrlth@hku.hk.
authors: Tai Hing
authors: TH
authors: Lam
authors: Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, N.T., Hong Kong SAR, China.
authors: Jean
authors: J
authors: Woo
authors: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors: Gabriel Matthew
authors: GM
authors: Leung
authors: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China; City University of New York, School of Public Health and Health Policy, New York.
authors: C Mary
authors: CM
authors: Schooling
mesh_terms: D000367:Age Factors; D000368:Aged; D018070:Biological Specimen Banks; D002318:Cardiovascular Diseases / Q000453:epidemiology* / Q000503:physiopathology; D002681:China; D015331:Cohort Studies; D004777:Environment; D004812:Epidemiologic Methods; D005260:Female; D006400:Hematocrit / Q000009:adverse effects*; D006801:Humans; D015994:Incidence; D008019:Life Style; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D018570:Risk Assessment; D012737:Sex Factors; D016019:Survival Analysis
keywords: Cardiovascular disease; Chinese; Coagulability; Environment-wide association study; Hematocrit