Summary
In women diagnosed as having category I primary obstetric antiphospholipid syndrome,
clinical characteristics and the risk of subsequent thromboembolic events and further
unsuccessful pregnancy has not been clearly documented. Women with unexplained obstetric
complications and no definite autoimmune systemic diseases were tested for lupus anticoagulant
(LA), IgG/ IgM anticardiolipin (aCL) and IgG/IgM anti-human β2-Glycoprotein I (aβ2GPI)
antibodies and diagnosed as having primary antiphospholipid syndrome (APS) in classification
category I on the basis of more than one laboratory criteria present in any combination.
Characteristics at the time of diagnosis and risk factors for subsequent clinical
events during a mean follow-up of 6.3 years were evaluated. Fifty-three of 600 women
studied were found to fulfil obstetric criteria and had more than one positive laboratory
test at the time of diagnosis. All the women were a CL and aβ2GPI positive, and 16
were also LA positive. This latter group (triple positivity) had distinct features
and had more frequently experienced previous thromboembolism (OR= 122.5, 95% CI 16–957,
p<0.001).They also had an increased rate of late pregnancy loss (OR=16.2, 95%CI 0.9–292,
p=0.01), and a higher IgG aβ2GPI titer at diagnosis (median, 25th and 75th percentile were 118, 37–962, vs. 23, 18–32, respectively, p<0.0001). During follow-up,
the rate of thromboembolic events was significantly higher in the group of women with
triple positivity and/ or previous thromboembolism (OR=57.5, 95% CI 2.7–1160, p=0.0004)
which were the only independent predictors of TE in the multivariate model. Recurrent
pregnancy loss took place in seven out of 47 women who had a new pregnancy. Triple
positivity and/or previous thromboembolism were again the only independent markers
(OR=34.4, 95% CI 3.5–335.1, p=0.003) of an unsuccessful new pregnancy. In conclusion,
in primary APS with pregnancy morbidity in classification category I, quite different
groups of patients may be identified on the basis of laboratory tests. Triple positivity
and/or a history of thromboembolism predict new TE events and new unsuccessful pregnancies.
Keywords
Antiphospholipid antibodies - thrombophilia - pregnancy