Free leptin index and PAPP-A: A first trimester maternal serum screening test for pre-eclampsia

Background: Prophylaxis with low-dose aspirin may reduce the risk of pre-eclampsia (PE) if introduced in first trimester. The performance of first trimester maternal serum screening for PE using free leptin index (fLI) and PAPP-A, where fLI = leptin/leptin soluble receptor was studied. Methods: First trimester serum samples from 126 PE pregnancies and 289 control pregnancies were studied. fLI and PAPP-A were converted into gestational age and maternal weight independent log MoM values of PAPP-A and fLI. The screening performance of markers was studied by receiver-operator-characteristics curves. The performance of population screening was estimated by Monte Carlo simulation. Results: fLI was significantly (p < 0.001) elevated [mean log MoM 0.2165 (SD: 0.2604)] compared to controls [mean log MoM -0.0368 (SD: 0.3132)] and PAPP-A was significantly (p < 0.001) reduced [mean log MoM -0.0133 (SD: 0.2661)] compared to controls [mean log MoM 0.0474 (SD: 0.2521)] in PE pregnancies. There was no correlation between fLI and PAPP-A in control or PE pregnancies. Combined fLI and PAPP-A screening for PE had estimated population detection rates of 22% and 35% for false positives rates of 6% and 12%, respectively. Conclusion: Combining PAPP-A and fLI improves screening performance for PE compared to single marker screening. Copyright © 2009 John Wiley & Sons, Ltd.