Value of autoantibodies to beta(2)-glycoprotein 1 in the diagnosis of antiphospholipid syndrome.
OBJECTIVE
To define the specificity and positive predictive value of anti-beta(2)-glycoprotein 1 (anti-beta(2)GP1) antibodies for the diagnosis of antiphospholipid syndrome (APS).


METHODS
We determined the presence of anticardiolipin (aCL) antibodies and anti-beta(2)-glycoprotein 1 (anti-beta(2)GP1) immunoglobulin (Ig) G and IgM in 191 consecutive sera from 191 patients and reviewed clinical data separately. aCL IgG and IgM were detected separately using commercial ELISA kits. Anti-beta(2)GP1 antibodies were detected with an in-house ELISA using beta(2)GP1.


RESULTS
Seven patients were diagnosed as having APS and 184 as having other diseases. Thirty-six patients were aCL-positive and 12 were anti-beta(2)GP1-positive, seven of these 12 were APS patients. The specificity for anti-beta(2)GP1 in our population was 97%, with a positive predictive value (PPV) of 58%. Among the aCL-positive patients, specificity was 90% and PPV 70-87%.


CONCLUSIONS
This study shows that anti-beta(2)GP1 antibodies have a higher specificity and PPV than aCL for APS. The PPV of anti-beta(2)GP1 was greater in aCL-positive than in all patients. We conclude that screening for anti-beta(2)GP1 antibodies in aCL-positive patients increases the specificity and the PPV of aCL testing. In addition, we show that there is no need to screen for anti-beta(2)GP1 antibodies in the absence of aCL antibodies and in the absence of strong clinical suspicion of APS.
Audrain
M A P
MA
Laboratoire d'Immunologie, Centre Hospitalier Universitaire, 9 quai Moncousu, 44093 Nantes cedex 1, France.
El-Kouri
D
D
Hamidou
M A
MA
Mioche
L
L
Ibara
A
A
Langlois
M-L
ML
Muller
J-Y
JY
D000328:Adult; D016736:Antiphospholipid Syndrome / Q000097:blood / Q000175:diagnosis* / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood*; D015415:Biomarkers; D002308:Cardiolipins / Q000097:blood / Q000276:immunology; D005260:Female; D006023:Glycoproteins / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D053482:beta 2-Glycoprotein I
D001323:Autoantibodies; D015415:Biomarkers; D002308:Cardiolipins; D006023:Glycoproteins; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D053482:beta 2-Glycoprotein I