Clinical and serological features of patients referred through a rheumatology triage system because of positive antinuclear antibodies

PLoS One. 2014 Apr 4;9(4):e93812. doi: 10.1371/journal.pone.0093812. eCollection 2014.


Background: The referral of patients with positive anti-nuclear antibody (ANA) tests has been criticized as an inappropriate use of medical resources. The utility of a positive ANA test in a central triage (CT) system was studied by determining the autoantibody profiles and clinical diagnoses of patients referred to rheumatologists through a CT system because of a positive ANA test.

Methods: Patients that met three criteria were included: (1) referred to Rheumatology CT over a three year interval; (2) reason for referral was a "positive ANA"; (3) were evaluated by a certified rheumatologist. The CT clinical database was used to obtain demographic and clinical information and a serological database was used to retrieve specific ANA and/or extractable nuclear antigen (ENA) test results. Clinical information was extracted from the consulting rheumatologist's report.

Results: 15,357 patients were referred through the CT system; 643 (4.1%) of these because of a positive ANA and of these 263 (40.9%) were evaluated by a certified rheumatologist. In 63/263 (24%) of ANA positive patients, the specialist provided a diagnosis of an ANA associated rheumatic disease (AARD) while 69 (26.2%) had no evidence of any disease; 102 (38.8%) had other rheumatologic diagnoses and 29 (11%) had conditions that did not meet AARD classification criteria. Of ANA positive archived sera, 15.1% were anti-DFS70 positive and 91.2% of these did not have an AARD.

Conclusions: This is the first study to evaluate the serological and clinical features of patients referred through a CT system because of a positive ANA. The spectrum of autoantibody specificities was wide with anti-Ro52/TRIM21 being the most common autoantibody detected. Approximately 15% of referrals had only antibodies to DFS70, the vast majority of which did not have clinical evidence for an AARD. These findings provide insight into the utility of autoantibody testing in a CT system.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Antinuclear / blood*
  • Antibodies, Antinuclear / immunology
  • Fluorescent Antibody Technique, Indirect
  • Humans
  • Immunoassay
  • Rheumatic Diseases / blood
  • Rheumatic Diseases / diagnosis*
  • Rheumatology / methods*
  • Ribonucleoproteins / immunology
  • Triage / methods*


  • Antibodies, Antinuclear
  • Ribonucleoproteins
  • SS-A antigen

Grant support

This project was funded and supported by resources from Mitogen Advanced Diagnostics Laboratory and as well as funds allocated to the Arthritis Society Research Chair by the University of Calgary, Division of Rheumatology, at the University of Calgary. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.