title: International multi-center evaluation of a novel chemiluminescence assay for the detection of anti-dsDNA antibodies.
abstract: OBJECTIVE
  Anti-double stranded desoxyribonucleic acid (anti-dsDNA) antibodies are considered fairly specific for systemic lupus erythematosus (SLE) and their quantification is useful for the clinical management of SLE patients. We assessed the diagnostic performance of the QUANTA Flash dsDNA chemiluminescent immunoassay (CIA) in comparison to an ELISA, using patients from five participating countries. The main focus was to evaluate the correlation between anti-dsDNA antibody results from the CIA and global SLE disease activity, as measured by the SLE Disease Activity Index 2000 (SLEDAI-2K).
  
  
  METHODS
  A total of 1431 samples (SLE, n = 843; disease controls, n = 588) from five countries (Canada, USA, Portugal, Sweden and Spain) were tested with QUANTA Flash dsDNA (Inova Diagnostics, San Diego, CA, USA). Data obtained with the QUANTA Lite dsDNA SC ELISA (Inova Diagnostics) were available for samples from three sites (Canada, USA and Sweden, n = 566). The SLEDAI-2K scores were available for 805 SLE patients and a cut-off of > 4 was used to define active disease.
  
  
  RESULTS
  QUANTA Flash dsDNA had a sensitivity of 54.3% for the diagnosis of SLE, combined with 89.8% specificity. Anti-dsDNA antibody levels were significantly higher (p < 0.0001) in active SLE (SLEDAI-2K > 4; n = 232; median value 83.0 IU/mL) versus the inactive patients (n = 573; median value 22.3 IU/mL), and the SLEDAI-2K scoring correlated with their dsDNA antibody levels (Spearman's rho = 0.44, p < 0.0001). Similar but less pronounced findings were also found for the ELISA, in relation to disease activity.
  
  
  CONCLUSIONS
  The QUANTA Flash dsDNA assay showed good clinical performance in a large international multi-center study. Additionally, the strong correlation between anti-dsDNA antibody results and SLEDAI-2K scores supported the potential utility of QUANTA Flash dsDNA for monitoring disease activity.
authors.affiliation: Department of Research, Inova Diagnostics, San Diego, CA, USA.
authors.forename: C
authors.initials: C
authors.lastname: Bentow
authors.affiliation: Department of Research, Inova Diagnostics, San Diego, CA, USA.
authors.forename: G
authors.initials: G
authors.lastname: Lakos
authors.affiliation: Department of Research, Inova Diagnostics, San Diego, CA, USA.
authors.forename: P
authors.initials: P
authors.lastname: Martis
authors.affiliation: Department of Research, Inova Diagnostics, San Diego, CA, USA.
authors.forename: E
authors.initials: E
authors.lastname: Wahl
authors.affiliation: Immunology Department, Centre Diagnostic Biomedic CDB, Hospital Clinic Barcelona, Barcelona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Garcia
authors.affiliation: Immunology Department, Centre Diagnostic Biomedic CDB, Hospital Clinic Barcelona, Barcelona, Spain.
authors.forename: O
authors.initials: O
authors.lastname: Viñas
authors.affiliation: Department of Autoimmune Diseases, Hospital Clinic Barcelona, Barcelona, Spain.
authors.forename: G
authors.initials: G
authors.lastname: Espinosa
authors.affiliation: Department of Autoimmune Diseases, Hospital Clinic Barcelona, Barcelona, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Cervera
authors.affiliation: Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Sjöwall
authors.affiliation: Rheumatology Research Unit, Instituto de Medicina Molecular, Universidade de Lisboa, Lisbon, Portugal.
authors.forename: D
authors.initials: D
authors.lastname: Carmona-Fernandes
authors.affiliation: Rheumatology Research Unit, Instituto de Medicina Molecular, Universidade de Lisboa, Lisbon, Portugal.
authors.forename: M J
authors.initials: MJ
authors.lastname: Santos
authors.affiliation: Dalhousie University Lupus Clinic, Halifax, Nova Scotia, Canada.
authors.forename: J G
authors.initials: JG
authors.lastname: Hanly
authors.affiliation: Department of Research, Inova Diagnostics, San Diego, CA, USA mmahler@inovadx.com.
authors.forename: M
authors.initials: M
authors.lastname: Mahler
mesh_terms: D000328:Adult; D000974:Antibodies, Antinuclear / Q000097:blood*; D002170:Canada; D004247:DNA / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D006801:Humans; D008163:Luminescent Measurements / Q000379:methods*; D008180:Lupus Erythematosus, Systemic / Q000175:diagnosis / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D011174:Portugal; D012680:Sensitivity and Specificity; D013030:Spain; D013548:Sweden; D014481:United States
chemical_list: D000974:Antibodies, Antinuclear; D004247:DNA
keywords: anti-dsDNA antibodies; autoantibodies; autoimmune disease; comparative study; diagnostic test; immunoassay; lupus; multicenter study; systemic lupus erythematosus