Clinical and serological features of patients referred through a rheumatology triage system because of positive antinuclear antibodies.
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.
Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.
Christie
C
Fitch-Rogalsky
Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.
Whitney
W
Steber
INOVA Diagnostics Inc., San Diego, California, United States of America.
Michael
M
Mahler
Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.
Terri
T
Lupton
Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.
Liam
L
Martin
Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.
Susan G
SG
Barr
Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.
Dianne P
DP
Mosher
Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.
James
J
Wick
Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.
Marvin J
MJ
Fritzler
D000974:Antibodies, Antinuclear / Q000097:blood* / Q000276:immunology; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007118:Immunoassay; D012216:Rheumatic Diseases / Q000097:blood / Q000175:diagnosis*; D012219:Rheumatology / Q000379:methods*; D012261:Ribonucleoproteins / Q000276:immunology; D014218:Triage / Q000379:methods*; D000099207:SS-A Antigen
D000974:Antibodies, Antinuclear; D012261:Ribonucleoproteins; D000099207:SS-A Antigen