Comparison of Fibrinogen/Albumin Ratio Between Women With Recurrent Pregnancy Loss and Those With First-Time Miscarriage

Abstract

The fibrinogen/albumin ratio (FAR) serves as a fine marker for systemic inflammation and coagulation. Its capacities in distinguishing the subjects with recurrent miscarriage from those with a first-time spontaneous miscarriage still remain to be established. To compare FAR between women with RPL and women who underwent a first miscarriage within the first trimester, and to assess the discriminative performance of FAR via an ROC analysis. A cross-sectional study for diagnostic comparison design, enrolling 120 first-trimester women into three groups (RPL, first-time miscarriage, healthy early pregnancy; n=40 each). Plasma fibrinogen and serum albumin levels were measured, and the FAR calculated. Differences between groups were tested through the appropriate parametric or nonparametric method. ROC analysis then evaluated AUC, optimal cut-points (Youden index), sensitivity, specificity, positive predictive value, and negative predictive value. Women with RPL in comparison to healthy pregnant controls were characterized by significantly elevated fibrinogen (403.50±15.62 mg/dL vs 307.25±45.35 mg/dL), decreased albumin (332.25±32.78 mg/dL vs 376.25±44.36 mg/dL), and remarkably increased FAR levels (1.2425±0.0699 vs 0.8289±0.1566) (all P<0.001). Compared with first miscarriage, the RPL group also recorded higher fibrinogen (403.50±15.62 mg/dL vs 354.75±28.99 mg/dL), lower albumin (332.25±32.78 mg/dL vs 345.50±39.68 mg/dL), and higher FAR (1.2425±0.0699 vs 1.0434±0.1023) (P≤0.002). ROC analysis was used to determine an FAR cut-point value of 0.975 for discriminating between RPL and healthy pregnancy (AUC=0.875; sensitivity 82.5%; specificity 87.5%) and 1.083 between RPL and first-time miscarriage (AUC=0.777; sensitivity 57.5%; specificity 65.0%). FAR is significantly elevated in women with RPL and greatly discriminates RPL and a healthy early pregnancy. It moderately discriminates between RPL and first-time miscarriage, suggesting that it could be useful as a screening/stratification biomarker but should not be used as a single diagnostic test for discriminating between miscarriage subtypes. External multicenter validation, harmonized assay methods, and incorporation of FAR into multimarker predictive models are recommended prior to clinical implementation.