title: ICARE improves antinuclear antibody detection by overcoming the barriers preventing accreditation.
abstract: BACKGROUND
  Antinuclear antibodies (ANA) are useful biomarkers for the diagnosis and the monitoring of rheumatic diseases. The American College of Rheumatology has stated that indirect immunofluorescence (IIF) analysis remains the gold standard for ANA screening. However, IIF is time consuming, subjective, not fully standardized and presents several issues for accreditation which is the process leading to ISO 15189 certification for medical laboratories. We propose an innovative tool for accreditation by using the quantitative evaluation of the automated image capture and analysis "ICARE" (Immunofluorescence for Computed Antinuclear antibody Rational Evaluation).
  
  
  METHODS
  We established the optimal screening dilution (1:160) and a fluorescence index (FI) cutoff for ICARE on a cohort of 91 healthy blood donors. Then, we evaluated performance of ICARE on a routine cohort of 236 patients. Precision parameters of ANA detection by IIF were evaluated according to ISO 15189.
  
  
  RESULTS
  ICARE showed an excellent concordance with visual evaluation (88%, Kappa=0.76) and significantly discriminated between weak to moderate (1:160-1:320 titers) and high (>1:320 titers) ANA levels. A significant correlation was found between FI and ANA titers (Spearman's ρ=0.67; P<0.0001). Using ICARE, we reported precision parameters such as repeatability (CV<13.8%) and reproducibility (CV<13.1%) as well as absence of inter-sample contamination for ANA detection by IIF according to ISO 15189 standards.
  
  
  CONCLUSIONS
  ICARE offers a precious help for the accreditation of IIF qualitative methods. This innovative quantitative approach is in adequacy with the process of continuous improvement of the quality of clinical laboratories.
authors.affiliation: Laboratoire d'Immunologie, Hôpital de la Conception, Assistance Publique-Hôpitaux de Marseille, France. Electronic address: daniel.bertin@ap-hm.fr.
authors.forename: Daniel
authors.initials: D
authors.lastname: Bertin
authors.affiliation: Laboratoire d'Immunologie, Hôpital de la Conception, Assistance Publique-Hôpitaux de Marseille, France.
authors.forename: Yassin
authors.initials: Y
authors.lastname: Mouhajir
authors.affiliation: Laboratoire d'Immunologie, Hôpital de la Conception, Assistance Publique-Hôpitaux de Marseille, France; Aix-Marseille Université, Laboratoire Adhésion et Inflammation, Marseille, France; INSERM, U1067, France; CNRS, U7333, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Bongrand
authors.affiliation: Laboratoire d'Immunologie, Hôpital de la Conception, Assistance Publique-Hôpitaux de Marseille, France; INSERM, U1076, France; Aix-Marseille Université, Laboratoire Endothélium, Pathologies Vasculaires et Cibles Thérapeutiques, Marseille, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Bardin
mesh_terms: D000068:Accreditation / Q000331:legislation & jurisprudence; D000328:Adult; D000974:Antibodies, Antinuclear / Q000097:blood*; D001327:Autoimmune Diseases / Q000097:blood*; D001331:Automation; D001774:Blood Chemical Analysis; D015331:Cohort Studies; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect / Q000592:standards*; D006801:Humans; D008297:Male; D008875:Middle Aged
chemical_list: D000974:Antibodies, Antinuclear
keywords: Accreditation; Antinuclear antibodies; Automated indirect immunofluorescence; Connective tissue diseases; HEp-2; ISO 15189; Image processing; Rheumatic diseases; Standardization