Prognostic impact of anticardiolipin antibodies in women with recurrent miscarriage negative for the lupus anticoagulant

BACKGROUND: Anticardiolipin antibodies (ACA) are found with increased prevalence in women with unexplained recurrent miscarriage (RM) but their impact on future pregnancy outcome in lupus anticoagulant (LAC) negative patients needs better quantification.

METHODS: The impact of a repeatedly positive ACA test on the chance of live birth in the next pregnancy after adjustment for relevant prognostic factors was studied in 147 RM patients who had been included in placebo-controlled trials of immunotherapy. Patients with LAC were excluded and none of the patients received therapy with anticoagulation or prednisone.

RESULTS: 60/147 patients (41%) were repeatedly ACA positive according to cut-off values derived from this study. The adjusted odds ratio (OR) for live birth among ACA positive patients was 0.36 (95% CI 0.2-0.7, P = 0.006). Using cut-off values derived from a normal population, the adjusted OR for live birth among ACA positive patients was 0.48 (95% CI 0.2-1.1, P = 0.10). Positivity for IgM ACA was found to be much stronger correlated to pregnancy outcome than IgG ACA.

CONCLUSIONS: In RM women not receiving anticoagulation or prednisone, the presence of ACA in the absence of LAC most likely reduces the chance of live birth by 36-48% compared with the absence of both ACA and LAC. This reduction is inferior to what has been reported from studies where no adjustments for prognostic variables were undertaken and LAC positive patients were included.