title: Analytical and biological variability in biomarker measurement in the Hispanic Community Health Study/Study of Latinos.
abstract: BACKGROUND
  Biomarker variability, which includes within-individual variability (CVI), between-individual variability (CVG) and methodological variability (CVP+A) is an important determinant of our ability to detect biomarker-disease associations. Estimates of CVIand CVGmay be population specific and little data exists on biomarker variability in diverse Hispanic populations. Hence, we evaluated all 3 components of biomarker variability in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) using repeat blood collections (n=58) and duplicate blood measurements (n=761-929 depending on the biomarker).
  
  
  METHODS
  We estimated the index of individuality (II) ((CVI+CVP+A)/CVG) for 41 analytes and evaluated differences in the II across sexes and age groups.
  
  
  RESULTS
  Biomarkers such as fasting glucose, triglycerides and ferritin had substantially higher inter-individual variability and lower II in HCHS/SOL as compared to the published literature. We also found significant sex-specific differences in the II for neutrophil count, platelet count, hemoglobin, % eosinophils and fasting glucose. The II for fasting insulin, post oral glucose tolerance test glucose and cystatin C was significantly higher among the 18-44y age group as compared to the 45+y age group.
  
  
  CONCLUSIONS
  The implications of these findings for determining biomarker-disease associations in Hispanic populations need to be evaluated in future studies.
authors.affiliation: Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, United States. Electronic address: thya0003@umn.edu.
authors.forename: Bharat
authors.initials: B
authors.lastname: Thyagarajan
authors.affiliation: Collaborative Studies Coordinating Center, Department of Biostatistics, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, United States.
authors.forename: Annie Green
authors.initials: AG
authors.lastname: Howard
authors.affiliation: Department of Public Health Sciences, Division of Biostatistics, Loyola University Chicago, Maywood, IL, United States.
authors.forename: Ramon
authors.initials: R
authors.lastname: Durazo-Arvizu
authors.affiliation: Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, United States.
authors.forename: John H
authors.initials: JH
authors.lastname: Eckfeldt
authors.affiliation: Department of Psychology, Behavioral Medicine Research Center, University of Miami, Miami, FL, United States.
authors.forename: Marc D
authors.initials: MD
authors.lastname: Gellman
authors.affiliation: Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, NY, United States.
authors.forename: Ryung S
authors.initials: RS
authors.lastname: Kim
authors.affiliation: Department of Preventive Medicine, Northwestern University, Chicago, IL, United States.
authors.forename: Kiang
authors.initials: K
authors.lastname: Liu
authors.affiliation: Department of Psychology, Behavioral Medicine Research Center, University of Miami, Miami, FL, United States.
authors.forename: Armando J
authors.initials: AJ
authors.lastname: Mendez
authors.affiliation: Department of Preventive Medicine, Northwestern University, Chicago, IL, United States.
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Penedo
authors.affiliation: Institute for Behavioral and Community Health, Graduate School of Public Health, San Diego State University, San Diego, CA, United States.
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Talavera
authors.affiliation: Collaborative Studies Coordinating Center, Department of Biostatistics, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, United States.
authors.forename: Marston E
authors.initials: ME
authors.lastname: Youngblood
authors.affiliation: Department of Preventive Medicine, Northwestern University, Chicago, IL, United States.
authors.forename: Lihui
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Collaborative Studies Coordinating Center, Department of Biostatistics, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, United States.
authors.forename: Daniela
authors.initials: D
authors.lastname: Sotres-Alvarez
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000097:blood*; D001772:Blood Cell Count; D001786:Blood Glucose / Q000032:analysis; D005215:Fasting; D005260:Female; D005293:Ferritins / Q000097:blood; D006306:Health Surveys; D006630:Hispanic or Latino; D006801:Humans; D008297:Male; D008875:Middle Aged; D012727:Sex Characteristics; D014280:Triglycerides / Q000097:blood; D055815:Young Adult
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D014280:Triglycerides; D005293:Ferritins
keywords: Analytical variation; Biomarker variability; Hispanics