title: Replication of LC-MS untargeted lipidomics results in patients with calcific coronary disease: An interlaboratory reproducibility study.
abstract: BACKGROUND
  Recently a lipidomics approach was able to identify perturbed fatty acyl chain (FAC) and sphingolipid moieties that could stratify patients according to the severity of coronary calcification, a form of subclinical atherosclerosis. Nevertheless, these findings have not yet been reproduced before generalising their application. The aim of this study was to evaluate the reproducibility of lipidomics approaches by replicating previous lipidomic findings in groups of patients with calcific coronary artery disease (CCAD).
  
  
  METHODS
  Patients were separated into the following groups based on their calcium score (CS); no calcification (CS: 0; n=26), mild calcification (CS: 1-250; n=27) and severe calcification (CS: >250; n=17). Two serum samples were collected from each patient and used for comparative analyses by 2 different laboratories, in different countries and time points using liquid chromatography coupled to mass spectrometry untargeted lipidomics methods.
  
  
  RESULTS
  Six identical metabolites differentiated patients with severe coronary artery calcification from those with no calcification were found by both laboratories independently. Additionally, relative intensities from the two analyses demonstrated high correlation coefficients. Phosphatidylcholine moieties with 18-carbon FAC were identified in lower intensities and 20:4 FAC in higher intensities in the serum of diseased group. Moreover, 3 common sphingomyelins were detected.
  
  
  CONCLUSIONS
  This is the first interlaboratory reproducibility study utilising lipidomics applications in general and specifically in patients with CCAD. Lipid profiling applications in patients with CCAD are very reproducible in highly specialised and experienced laboratories and could be applied in clinical practice in order to spare patients diagnostic radiation.
authors.affiliation: Department of Public Health and Clinical Medicine, Umeå University And Heart Centre, Umeå, Sweden.
authors.forename: Demir
authors.initials: D
authors.lastname: Djekic
authors.affiliation: Computational Life Science Cluster, Department of Chemistry, Umeå University, Umeå, Sweden; Bioinformatics for Life Sciences (BILS), Sweden.
authors.forename: Rui
authors.initials: R
authors.lastname: Pinto
authors.affiliation: Section of Biomolecular Medicine, Division of Computational and Systems Medicine, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, SW72AZ, London, UK.
authors.forename: Panagiotis A
authors.initials: PA
authors.lastname: Vorkas
authors.affiliation: Department of Public Health and Clinical Medicine, Umeå University And Heart Centre, Umeå, Sweden. Electronic address: Michael.henein@umu.se.
authors.forename: Michael Y
authors.initials: MY
authors.lastname: Henein
mesh_terms: D000368:Aged; D002853:Chromatography, Liquid / Q000379:methods / Q000592:standards; D019411:Clinical Laboratory Techniques / Q000379:methods / Q000592:standards*; D003324:Coronary Artery Disease / Q000097:blood* / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D008055:Lipids / Q000097:blood*; D008297:Male; D013058:Mass Spectrometry / Q000379:methods / Q000592:standards*; D055432:Metabolomics / Q000379:methods / Q000592:standards*; D008875:Middle Aged; D015203:Reproducibility of Results; D061205:Vascular Calcification / Q000097:blood* / Q000000981:diagnostic imaging
chemical_list: D008055:Lipids
keywords: Calcific coronary disease; Coronary artery disease; Lipidomics; Metabolomics; Reproducibility