Low Molecular Weight Heparin For Prevention Of Placenta-Mediated Pregnancy Complications: An Individual Patient Data Meta-Analysis

Introduction Placenta-mediated pregnancy complications (PMPC) include pre-eclampsia, late pregnancy loss, placental abruption, and the small-for-gestational age (SGA) newborn. They are leading causes of maternal, fetal, and neonatal morbidity and mortality. Affected women are at an elevated risk of recurrence in subsequent pregnancies. We completed a pooled summary-based (i.e. study level) meta-analysis that strongly suggests that low-molecular-weight heparin (LMWH) reduces the risk of recurrent PMPCs. However, our study-level meta-analysis was limited by high clinical and statistical heterogeneity likely due to the inclusion of women with heterogeneous prior PMPCs and trial designs (e.g. single vs multi-center trials). To address these limitations, the trialists agreed to conduct an individual patient data meta-analysis to identify sources of heterogeneity including exploring which patients benefit from LMWH and which outcomes are prevented. Methods We conducted a systematic review to identify randomised controlled trials that were eligible to contribute individual patient data to a meta-analysis to evaluate the effectiveness of LMWH for reducing the risk of PMPC in women with prior PMPCs. The primary outcome was a composite of early-onset or severe pre-eclampsia, birth of an SGA newborn 20 weeks), or placental abruption leading to delivery. Individual patient data from eligible women were re-coded in a prescribed format and combined in a common dataset for analysis. All studies were assessed for risk of bias. Results Data from 1049 women in nine trials were analysed; Participants were mostly Caucasian (88%) with a mean age of 31.518 had thrombophilia. 525 women were randomised to LMWH and 524 to no LMWH. In our primary outcome analysis, LMWH did not significantly reduce the risk of recurrent PMPCs (LMWH 60/459 (13.1%) vs. no LMWH 92/449 (20.5%) p=0.1). Significant heterogeneity was noted between single center and multi-center trials. In multi-center trials, LMWH reduced HELLP (p=0.03) but none of the other secondary outcomes, whereas in single center trials LMWH reduced all of the secondary outcomes. In sub-group analysis, in multi-center trials LMWH reduced the primary outcome in women with prior abruption (p Conclusions In this individual patient data meta-analysis, LMWH does not appear to reduce the risk of recurrent PMPC in women with prior PMPC. Promising results suggest that women with prior abruption may benefit from LMWH but this should be replicated in future multi-center trials. PROSPERO registration:CRD42013006249 Disclosures Rodger: Biomerieux: Honoraria, Research Funding. Off Label Use: Low Molecular Weight Heparin to prevent pregnancy complications. de Vries: Pfizer: Research Funding. Rey: Leo Pharma: Other: Travel Grant. Gris: Sanofi: Consultancy, Membership on an entity9s Board of Directors or advisory committees, Research Funding; Stago: Consultancy, Membership on an entity9s Board of Directors or advisory committees, Research Funding, Speakers Bureau; Leo Pharma: Consultancy, Speakers Bureau; LFB: Consultancy, Membership on an entity9s Board of Directors or advisory committees, Research Funding, Speakers Bureau; Baxter: Research Funding; BI: Speakers Bureau; Bayer: Speakers Bureau; BMS: Speakers Bureau. Schleussner: Bayer: Speakers Bureau; Pfizer: Research Funding, Speakers Bureau; Merck: Research Funding, Speakers Bureau. Middeldorp: GSK/Aspen: Research Funding; Bayer: Consultancy, Speakers Bureau; BI: Consultancy, Speakers Bureau; BMS: Consultancy, Research Funding, Speakers Bureau; Pfizer: Consultancy, Research Funding, Speakers Bureau; Daiichi-Sankyo: Consultancy, Speakers Bureau. Bates: Eli Lilly Canada: Other: I hold the Eli Lilly Canada/May Cohen Chair in Women9s Health. Eli Lilly Canada provides unrestricted funding for partial salary support through this Chair. Eli Lilly Canada does not manufacture/distribute drugs relevant to the topic to be discussed..