Background/Purpose: To describe the prevalence of non-conventional APL in patients with obstetrical APS pregnancy adverse outcome without conventional APL and the impact of treatment on pregnancy outcome.

Methods: The inclusion criteria were: (1) ≥3 early miscarriages less than 10 weeks of gestation; (2) intrauterine fetal death ≥10 weeks of gestation; (3) preeclampsia, prematurity <34 weeks of gestation related to placental insufficiency; (4) absence of inherited thrombophilia (V Leiden and II homozygous mutations, proteins C, S, ATIII deficiencies) and of conventional APL (LA, ACL IgG/M, anti- β₂GPI IgG/M). 96 patients with clinical obstetrical APS criteria were tested for anti-phosphatidylethanolamine (aPE) IgG/M, anti-prothrombin/phosphatidylserine (anti-PS/PT) IgG/M and anti-annexin V IgG. Pregnancies losses rates were compared between APS, non-conventional APS and non-APL and in untreated pregnancies to treated ones for each group. A control group of 47 healthy pregnant patients without any pregnancy complication have been selected from Bichat Hospital, without any age difference with clinical APS and without conventional APL (31±6 versus 33±4 years; p>0.05). A control group of patients with confirmed APS (Sydney criteria) (n=83) was also selected.

Results: Using the cut-offs (ROC), 65/96 (68%) patients have been considered as non-conventional APS and compared to 83 APS and 31 patients without APL. Among these 65 non-conventional APS, recurrent miscarriage was noted in 44 (46%) cases, intrauterine fetal deaths in 38 (40%) cases, premature term<34 weeks of gestation in 25 (27%) cases, preeclampsia and/or HELLP syndrome in 25 (26%) cases and thrombosis in 14 (15%) cases. The obstetrical history in non-conventional APS did not differ in comparison to confirmed APS. The frequencies of anti-annexin V IgG antibodies tended to be more frequent in non-conventional APS (88% versus 73%; p=0.06), and those of anti-PE IgG and M were similar. The anti-PS/PT IgG and M antibodies were more frequent in confirmed APS than in non-conventional APS (63% and 37% versus 4% and 5%, p<0.0001). Overall 261 pregnancies in patients with non-conventional APS were compared to 81 pregnancies of confirmed APS and 132 pregnancies from non-APL group. 136/474 (29%) patients have been treated during pregnancies and treatment significantly increased the rate of live birth (26% in untreated versus 72% in treated pregnancies, p<0.0001). In univariate analyses, treatment effect on pregnancies losses was similar in patients with APS and non-conventional APS, with odds ratio at 3.3 [95% CI; 1.8 to 6.1] and 6.9 [95% CI; 3.9 to 12.3] (p=0.49) and significantly more important for the 2 APS groups pooled versus non-APL group (OR at 1.9 [95% CI; 1.1 to 3.5] for non-APL group versus 5.3 [95% CI; 3.5 to 8.1] for APS groups, p=0.0025).

Conclusion:  In this study 68% of patients with clinical criteria for obstetrical APS seronegative for conventional APL have non-conventional APL. These patients have a significant decrement of pregnancy losses if they receive treatment for APS during their pregnancy.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/non-conventional-antiphospholipid-antibodies-in-patients-with-clinical-obstetrical-aps-prevalence-and-pregnancies-treatment-efficacy/