Antiphospholipid antibody panels and recurrent pregnancy loss: Prevalence of anticardiolipin antibodies compared with other antiphospholipid antibodies

Objective: To describe the prevalence of antiphospholipid antibodies in additi Design: Retrospective data analysis of test results from an antiphospholipid antibody panel. Setting: A university-based private patient referral center. Patients: Included 866 women with a history of recurrent pregnancy loss and 288 parous women without a history of reproductive problems. Interventions: None. Main Outcome Measures: Enzyme-Linked immunosorbant assay, with referenced standards and known positive and negative sera on each plate, was used to measure anticardiolipin, antiphosphatidyl inositol, antiphosphatidylglycerol, antiphosphatidylserine, and antiphosphatidylethanolamine. Statistical analyses used the two-tailed Fisher's exact test. Results: Positive anticardiolipin antibodies were detected in 17.3% of patients with recurrent pregnancy loss compared with only 4% in the control population. Eighty-seven of the 866 women (10.1%) were negative for anticardiolipin antibodies but had positive levels of another antiphospholipid antibody. Isolated positive antibody levels occurred most frequently in the immunoglobulin (Ig) G class of phosphatidylinositol, cardiolipin, and phosphatidylethanolamine. Isolated IgA, was only found in phosphatidylethanolamine. Conclusion: In women with recurrent pregnancy loss, 150 of 866 (17.3%) had positive anticardiolipin antibodies. Additionally, 87 of 866 (10.1%) women were positive for another antiphospholipid antibody. Patient demographics were similar in both groups. We emphasize the importance of careful standardization, quality control, and interpretation of positive results.