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 valuable marker of systemic inflammation and coagulation. However, its capacity to distinguish patients with recurrent pregnancy loss (RPL) from those experiencing a first-time spontaneous miscarriage has yet to be established. This study aimed to compare FAR levels between women with RPL and those who underwent a first-trimester miscarriage, as well as to assess the discriminative performance of FAR using receiver operating characteristic (ROC) curve analysis. In this cross-sectional, diagnostic-comparison study, 120 women in their first trimester were enrolled and divided into three groups: RPL, first-time miscarriage, and healthy early pregnancy (n=40 per group). Plasma fibrinogen and serum albumin levels were measured, and the FAR was calculated. Differences between the groups were analyzed using appropriate parametric or nonparametric methods. Subsequently, ROC analysis was performed to evaluate the area under the curve (AUC), optimal cut-off points (via the Youden index), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Women with RPL, compared with 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 markedly increased FAR levels (1.2425±0.0699 vs 0.8289±0.1566) (all P<0.001). Compared with the first-time miscarriage group, the RPL group also showed 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 identified an FAR cut-off value of 0.975 for discriminating between RPL and healthy pregnancy (AUC=0.875; sensitivity 82.5%; specificity 87.5%) and 1.083 for discriminating between RPL and first-time miscarriage (AUC=0.777; sensitivity 57.5%; specificity 65.0%). FAR is significantly elevated in women with RPL and strongly discriminates between RPL and 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 distinguishing between miscarriage subtypes. External multicenter validation, harmonized assay methods, and incorporation of FAR into multimarker predictive models are recommended prior to clinical implementation.