title: Detection of antinuclear antibodies by automated indirect immunofluorescence analysis.
abstract: BACKGROUND
  Testing for antinuclear antibodies is useful for the diagnosis of systemic rheumatic diseases. Automated systems for image acquisition and interpretation of indirect immunofluorescence-based tests are increasingly used. The diagnostic performance of such automated approach in untreated patients has not been reported.
  
  
  METHODS
  Antinuclear antibodies were measured by automated indirect immunofluorescence using Zenit G. Sight on HEp2 and HEp2000 substrate in 268 consecutive samples submitted to the laboratory for antinuclear antibody testing, and in 231 patients with a systemic rheumatic disease at the time of diagnosis, 143 blood donors, 134 patients with chronic fatigue syndrome, and 133 diseased controls.
  
  
  RESULTS
  Image acquisition by G-Sight was of high quality. The accuracy of pattern assignment was limited. There was a significant correlation between automated estimation of fluorescence intensity (probability index of positivity) and end-point titer. Probability index interval specific likelihood ratios for systemic rheumatic disease increased with increasing level of positivity probability. With the HEp-2 substrate, the likelihood ratio for systemic lupus erythematosus was 0.06, 0.4, 6.8, 12.1, and 43.9 for a probability measure of positivity of ≤10, 11-≤30, 31-≤50, 51-≤85, and >85, respectively.
  
  
  CONCLUSIONS
  Quantitative data generated by automated image acquisition facilitates standardized interpretation.
authors.affiliation: Experimental Laboratory Immunology, Catholic University Leuven, Leuven, Belgium. xavier.bossuyt@uz.kuleuven.ac.be
authors.forename: Xavier
authors.initials: X
authors.lastname: Bossuyt
authors.forename: Sarah
authors.initials: S
authors.lastname: Cooreman
authors.forename: Heidi
authors.initials: H
authors.lastname: De Baere
authors.forename: Patrick
authors.initials: P
authors.lastname: Verschueren
authors.forename: René
authors.initials: R
authors.lastname: Westhovens
authors.forename: Daniel
authors.initials: D
authors.lastname: Blockmans
authors.forename: Godelieve
authors.initials: G
authors.lastname: Mariën
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000974:Antibodies, Antinuclear / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D015673:Fatigue Syndrome, Chronic / Q000097:blood* / Q000175:diagnosis; D005260:Female; D057166:High-Throughput Screening Assays; D006801:Humans; D007118:Immunoassay / Q000592:standards*; D008180:Lupus Erythematosus, Systemic / Q000097:blood* / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D011336:Probability; D015203:Reproducibility of Results; D012216:Rheumatic Diseases / Q000097:blood* / Q000175:diagnosis; D012680:Sensitivity and Specificity
chemical_list: D000974:Antibodies, Antinuclear; D015415:Biomarkers