title: A Negative Antinuclear Antibody Does Not Indicate Autoantibody Negativity in Myositis: Role of Anticytoplasmic Antibody as a Screening Test for Antisynthetase Syndrome.
abstract: To evaluate the utility of anticytoplasmic autoantibody (anti-CytAb) in antisynthetase antibody-positive (anti-SynAb+) patients.
  
  
  
  Anti-SynAb+ patients were evaluated for antinuclear antibody (ANA) and anti-CytAb [cytoplasmic staining on indirect immunofluorescence (IIF)] positivity. Anti-SynAb+ patients included those possessing anti-Jo1 and other antisynthetase autoantibodies. Control groups included scleroderma, systemic lupus erythematosus, Sjögren syndrome, rheumatoid arthritis, and healthy subjects. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy of anti-CytAb, and ANA were assessed. Anti-CytAb and ANA testing was done by IIF on human epithelial cell line 2, both reported on each serum sample without knowledge of the clinical diagnosis or final anti-SynAb results.
  
  
  
  Anti-SynAb+ patients (n = 202; Jo1, n = 122; non-Jo1, n = 80) between 1985-2013 with available serum samples were assessed. Anti-CytAb showed high sensitivity (72%), specificity (89%), NPV (95%), and accuracy (86%), but only modest PPV (54%) for anti-SynAb positivity. In contrast, ANA showed only modest sensitivity (50%) and poor specificity (6%), PPV (9%), NPV (41%), and accuracy (12%). Positive anti-CytAb was significantly greater in the anti-SynAb+ patients than ANA positivity (72% vs 50%, p < 0.001), and 81/99 (82%) ANA-negative patients in the anti-SynAb+ cohort had positive anti-CytAb. In contrast, the control groups showed high rates for ANA positivity (93.5%), but very low rates for anti-CytAb positivity (11.5%). Combining anti-CytAb or Jo1 positivity showed high sensitivity (92%) and specificity (89%) for identification of anti-SynAb+ patients.
  
  
  
  Assessing patients for anti-CytAb serves as an excellent screen for anti-SynAb+ patients using simple IIF. Cytoplasmic staining should be assessed and reported for patients suspected of having antisynthetase syndrome and a negative ANA should not be used to exclude this diagnosis.
authors.affiliation: From the Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA. aggarwalr@upmc.edu.|R. Aggarwal, MD, MS, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; N. Dhillon, MD, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; N. Fertig, BS, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; D. Koontz, BS, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; Z. Qi, PhD, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; C.V. Oddis, MD, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine. aggarwalr@upmc.edu.
authors.forename: Rohit
authors.initials: R
authors.lastname: Aggarwal
authors.affiliation: From the Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.|R. Aggarwal, MD, MS, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; N. Dhillon, MD, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; N. Fertig, BS, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; D. Koontz, BS, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; Z. Qi, PhD, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; C.V. Oddis, MD, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine.
authors.forename: Namrata
authors.initials: N
authors.lastname: Dhillon
authors.affiliation: From the Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.|R. Aggarwal, MD, MS, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; N. Dhillon, MD, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; N. Fertig, BS, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; D. Koontz, BS, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; Z. Qi, PhD, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; C.V. Oddis, MD, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine.
authors.forename: Noreen
authors.initials: N
authors.lastname: Fertig
authors.affiliation: From the Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.|R. Aggarwal, MD, MS, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; N. Dhillon, MD, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; N. Fertig, BS, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; D. Koontz, BS, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; Z. Qi, PhD, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; C.V. Oddis, MD, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine.
authors.forename: Diane
authors.initials: D
authors.lastname: Koontz
authors.affiliation: From the Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.|R. Aggarwal, MD, MS, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; N. Dhillon, MD, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; N. Fertig, BS, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; D. Koontz, BS, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; Z. Qi, PhD, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; C.V. Oddis, MD, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine.
authors.forename: Zengbiao
authors.initials: Z
authors.lastname: Qi
authors.affiliation: From the Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.|R. Aggarwal, MD, MS, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; N. Dhillon, MD, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; N. Fertig, BS, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; D. Koontz, BS, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; Z. Qi, PhD, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine; C.V. Oddis, MD, Division of Rheumatology and Clinical Immunology, University of Pittsburgh School of Medicine.
authors.forename: Chester V
authors.initials: CV
authors.lastname: Oddis
mesh_terms: D000328:Adult; D000974:Antibodies, Antinuclear / Q000032:analysis*; D005260:Female; D006801:Humans; D008297:Male; D009220:Myositis / Q000097:blood / Q000175:diagnosis*; D012680:Sensitivity and Specificity
chemical_list: D000974:Antibodies, Antinuclear
keywords: ANTINUCLEAR ANTIBODY; ANTISYNTHETASE AUTOANTIBODY; ANTISYNTHETASE SYNDROME; CYTOPLASMIC ANTIBODY STAINING; DERMATOMYOSITIS; POLYMYOSITIS