title: Comparison of serum, EDTA plasma and P100 plasma for luminex-based biomarker multiplex assays in patients with chronic obstructive pulmonary disease in the SPIROMICS study.
abstract: BACKGROUND
  As a part of the longitudinal Chronic Obstructive Pulmonary Disease (COPD) study, Subpopulations and Intermediate Outcome Measures in COPD study (SPIROMICS), blood samples are being collected from 3200 subjects with the goal of identifying blood biomarkers for sub-phenotyping patients and predicting disease progression. To determine the most reliable sample type for measuring specific blood analytes in the cohort, a pilot study was performed from a subset of 24 subjects comparing serum, Ethylenediaminetetraacetic acid (EDTA) plasma, and EDTA plasma with proteinase inhibitors (P100).
  
  
  METHODS
  105 analytes, chosen for potential relevance to COPD, arranged in 12 multiplex and one simplex platform (Myriad-RBM) were evaluated in duplicate from the three sample types from 24 subjects. The reliability coefficient and the coefficient of variation (CV) were calculated. The performance of each analyte and mean analyte levels were evaluated across sample types.
  
  
  RESULTS
  20% of analytes were not consistently detectable in any sample type. Higher reliability and/or smaller CV were determined for 12 analytes in EDTA plasma compared to serum, and for 11 analytes in serum compared to EDTA plasma. While reliability measures were similar for EDTA plasma and P100 plasma for a majority of analytes, CV was modestly increased in P100 plasma for eight analytes. Each analyte within a multiplex produced independent measurement characteristics, complicating selection of sample type for individual multiplexes.
  
  
  CONCLUSIONS
  There were notable detectability and measurability differences between serum and plasma. Multiplexing may not be ideal if large reliability differences exist across analytes measured within the multiplex, especially if values differ based on sample type. For some analytes, the large CV should be considered during experimental design, and the use of duplicate and/or triplicate samples may be necessary. These results should prove useful for studies evaluating selection of samples for evaluation of potential blood biomarkers.
authors.affiliation: Cystic Fibrosis/Pulmonary Research and Treatment Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. woneal@med.unc.edu.
authors.forename: Wanda K
authors.initials: WK
authors.lastname: O'Neal
authors.forename: Wayne
authors.initials: W
authors.lastname: Anderson
authors.forename: Patricia V
authors.initials: PV
authors.lastname: Basta
authors.forename: Elizabeth E
authors.initials: EE
authors.lastname: Carretta
authors.forename: Claire M
authors.initials: CM
authors.lastname: Doerschuk
authors.forename: R Graham
authors.initials: RG
authors.lastname: Barr
authors.forename: Eugene R
authors.initials: ER
authors.lastname: Bleecker
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Christenson
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Curtis
authors.forename: Meilan K
authors.initials: MK
authors.lastname: Han
authors.forename: Nadia N
authors.initials: NN
authors.lastname: Hansel
authors.forename: Richard E
authors.initials: RE
authors.lastname: Kanner
authors.forename: Eric C
authors.initials: EC
authors.lastname: Kleerup
authors.forename: Fernando J
authors.initials: FJ
authors.lastname: Martinez
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Miller
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Peters
authors.forename: Stephen I
authors.initials: SI
authors.lastname: Rennard
authors.forename: Mary Beth
authors.initials: MB
authors.lastname: Scholand
authors.forename: Ruth
authors.initials: R
authors.lastname: Tal-Singer
authors.forename: Prescott G
authors.initials: PG
authors.lastname: Woodruff
authors.forename: David J
authors.initials: DJ
authors.lastname: Couper
authors.forename: Sonia M
authors.initials: SM
authors.lastname: Davis
mesh_terms: D015415:Biomarkers / Q000097:blood*; D003948:Diagnostic Techniques, Respiratory System; D004492:Edetic Acid / Q000737:chemistry*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010949:Plasma / Q000378:metabolism*; D011480:Protease Inhibitors; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood*; D015203:Reproducibility of Results; D044967:Serum / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D011480:Protease Inhibitors; D004492:Edetic Acid