title: Automated indirect immunofluorescence microscopy enables the implementation of a quantitative internal quality control system for anti-nuclear antibody (ANA) analysis.
abstract: BACKGROUND
  Screening for anti-nuclear antibodies by indirect immunofluorescence (ANA-IIF) remains mandatory in the serological work-up of connective tissue diseases. Recently, automated approaches were introduced that may improve harmonization. Here, we investigated whether the introduction of automated ANA-IIF and more specifically the use of its quantitative measure, could improve ANA-IIF internal quality control (IQC) management.
  
  
  METHODS
  We retrospectively reviewed results of two cohorts of routine samples and parallel IQC data collected from January 2010 to February 2013 and from February to mid October 2013. For the first cohort, data were collected using conventional microscopy. The second cohort was analyzed by an automated ANA-IIF microscope (Zenit G sight, A. Menarini). Retrospectively, we evaluated the applicability of the probability index (PI) of control material measurements and patient results for IQC management based on Westgard multirules. This approach was also compared with monthly monitoring of the %ANA-IIF positive samples.
  
  
  RESULTS
  In our historical data set, we showed that monitoring of %ANA positives identified systematic errors that were not detected by monitoring control material results. Data resulting from automated microscopy showed that PI measurements on control material remained stable within the observed period and that Westgard multirules can be used for IQC follow-up. Parallel monitoring of the daily median patient PI and the monthly %ANA positives, showed that the daily median was a sensitive and fast tool for detecting systematic errors.
  
  
  CONCLUSIONS
  The introduction of the automated ANA-IIF microscope could enable objective IQC procedures and should be considered an important step forward in ANA-IIF harmonization.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Maenhout
authors.forename: Carolien
authors.initials: C
authors.lastname: Bonroy
authors.forename: Charlotte
authors.initials: C
authors.lastname: Verfaillie
authors.forename: Veronique
authors.initials: V
authors.lastname: Stove
authors.forename: Katrien
authors.initials: K
authors.lastname: Devreese
mesh_terms: D000974:Antibodies, Antinuclear / Q000032:analysis*; D001331:Automation; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D008856:Microscopy, Fluorescence; D011786:Quality Control
chemical_list: D000974:Antibodies, Antinuclear