Occupational exposure in ANCA-positive patients: a case-control study.
BACKGROUND
Antineutrophil cytoplasmic autoantibodies (ANCA) are valuable biomarkers for the diagnosis and follow-up of small vessel vasculitis. The role of ANCA has not yet been fully established, but genetic, infectious, and/or environmental factors may increase susceptibility to these diseases. We performed an epidemiologic study to investigate whether the presence of ANCA was associated with silica or any other form of occupational exposure, regardless of the underlying disease.


METHODS
All consecutive ANCA-positive patients recorded at the institution's Laboratory of Immunology between 1990 and 2000 were included. Patients hospitalized in a unit of internal medicine matched for age and gender were selected as controls (two controls/case). Qualitative and semiquantitative professional exposure and smoking habits were analyzed by five experts blind to the diagnosis.


RESULTS
Univariate analysis showed that patients who reported dust exposure had a 2.6 greater risk of being ANCA-positive (P= 0.007) (odds ratio 2.6; 95% CI 1.3 to 5.3) and individuals with professional exposure to silica had a 3.4 higher risk of being ANCA-positive (P= 0.03) (odds ratio 3.4; 95% CI 1.1 to 9.9). None of the other environmental factors or smoking habits were different between ANCA-positive patients and controls. There was no difference in silica exposure between patients with cytoplasmic ANCA (c-ANCA), perinuclear ANCA (p-ANCA), or atypical ANCA. Semiquantitative analysis showed a dose effect of silica exposure with a nearly sevenfold greater risk of being ANCA-positive compared to controls (P= 0.02) (odds ratio 6.9; 95% CI 1.3 to 35.1).


CONCLUSIONS
These results support the hypothesis that the presence of ANCA in plasma might at least partially be related to occupational exposure.
Beaudreuil
Séverine
S
Department of Nephrology and Clinical Immmunology, CHU Bretonneau, Tours, France.
Lasfargues
Gérard
G
Lauériere
Laurence
L
El Ghoul
Zen
Z
Fourquet
Florence
F
Longuet
Cédric
C
Halimi
Jean-Michel
JM
Nivet
Hubert
H
Büchler
Matthias
M
D000368:Aged; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D004305:Dose-Response Relationship, Drug; D004391:Dust; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000209:etiology; D016273:Occupational Exposure; D012307:Risk Factors; D012822:Silicon Dioxide / Q000008:administration & dosage / Q000009:adverse effects; D014657:Vasculitis / Q000209:etiology
D019268:Antibodies, Antineutrophil Cytoplasmic; D015415:Biomarkers; D004391:Dust; D012822:Silicon Dioxide