title: Comparison of Collection Methods for Fecal Samples for Discovery Metabolomics in Epidemiologic Studies.
abstract: The gut metabolome may be associated with the incidence and progression of numerous diseases. The composition of the gut metabolome can be captured by measuring metabolite levels in the feces. However, there are little data describing the effect of fecal sample collection methods on metabolomic measures.
  
  
  
  We collected fecal samples from 18 volunteers using four methods: no solution, 95% ethanol, fecal occult blood test (FOBT) cards, and fecal immunochemical test (FIT). One set of samples was frozen after collection (day 0), and for 95% ethanol, FOBT, and FIT, a second set was frozen after 96 hours at room temperature. We evaluated (i) technical reproducibility within sample replicates, (ii) stability after 96 hours at room temperature for 95% ethanol, FOBT, and FIT, and (iii) concordance of metabolite measures with the putative "gold standard," day 0 samples without solution.
  
  
  
  Intraclass correlation coefficients (ICC) estimating technical reproducibility were high for replicate samples for each collection method. ICCs estimating stability at room temperature were high for 95% ethanol and FOBT (median ICC > 0.87) but not FIT (median ICC = 0.52). Similarly, Spearman correlation coefficients (rs) estimating metabolite concordance with the "gold standard" were higher for 95% ethanol (median rs= 0.82) and FOBT (median rs= 0.70) than for FIT (median rs= 0.40).
  
  
  
  Metabolomic measurements appear reproducible and stable in fecal samples collected with 95% ethanol or FOBT. Concordance with the "gold standard" is highest with 95% ethanol and acceptable with FOBT.
  
  
  
  Future epidemiologic studies should collect feces using 95% ethanol or FOBT if interested in studying fecal metabolomics. Cancer Epidemiol Biomarkers Prev; 25(11); 1483-90. ©2016 AACR.
authors.affiliation: Metabolic Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland. erikka.loftfield@nih.gov.
authors.forename: Erikka
authors.initials: E
authors.lastname: Loftfield
authors.affiliation: Metabolic Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: Emily
authors.initials: E
authors.lastname: Vogtmann
authors.affiliation: Biostatistics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: Joshua N
authors.initials: JN
authors.lastname: Sampson
authors.affiliation: Metabolic Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: Steven C
authors.initials: SC
authors.lastname: Moore
authors.affiliation: Microbiome Program, Center for Individualized Medicine, Mayo Clinic, Rochester, Minnesota.|Department of Surgery, Mayo Clinic, Rochester, Minnesota.
authors.forename: Heidi
authors.initials: H
authors.lastname: Nelson
authors.affiliation: Health Sciences Research, Mayo Clinic, Rochester, Minnesota.|Department of Pediatrics, University of California San Diego, San Diego, California.
authors.forename: Rob
authors.initials: R
authors.lastname: Knight
authors.affiliation: Microbiome Program, Center for Individualized Medicine, Mayo Clinic, Rochester, Minnesota.|Department of Surgery, Mayo Clinic, Rochester, Minnesota.|Department of Computer Science and Engineering, University of California San Diego, San Diego, California.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Chia
authors.affiliation: Metabolic Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: Rashmi
authors.initials: R
authors.lastname: Sinha
mesh_terms: D000328:Adult; D015925:Cryopreservation; D016021:Epidemiologic Studies; D005243:Feces / Q000737:chemistry*; D005260:Female; D006801:Humans; D008297:Male; D055432:Metabolomics / Q000379:methods*; D008875:Middle Aged; D015203:Reproducibility of Results; D013048:Specimen Handling / Q000379:methods*; D055815:Young Adult