Construction and validation of a risk prediction model for recurrent pregnancy losses in patients with positive antiphospholipid antibodies.

To identify independent risk factors for recurrent pregnancy loss (RPL) among antiphospholipid antibody (aPL)-positive individuals who were either in early pregnancy (≤12 weeks' gestation) or not pregnant, and to develop and validate a risk prediction model to support early clinical risk stratification and intervention. We retrospectively analyzed 197 aPL-positive patients with a history of adverse pregnancy outcomes. Of the 197 aPL-positive patients, 31 met the diagnostic criteria for APS, and 166 had isolated aPL positivity. The patients were divided into an RPL group (n = 76) or a non-RPL group (n = 121) based on the occurrence of RPL, and were then randomly assigned (7:3) into a training set (n = 138) and a validation set (n = 59). Candidate predictors were screened using univariate logistic regression and entered into multivariate logistic regression to identify independent risk factors. Model discrimination and clinical utility were assessed using the area under the curve (AUC), calibration curves, and decision curve analysis (DCA), and a nomogram was subsequently constructed to facilitate individualized risk estimation. The results showed that coagulation factor V, coagulation factor VIII, TAT, ANA, and D-dimer were independent risk factors for RPL in aPL-positive individuals (either within the first 12 weeks of pregnancy or non-pregnant). The prediction model developed based on these factors demonstrated good discrimination, with AUC values of 0.787 and 0.711 in the training and validation sets, respectively. DCA confirmed that the model provided net clinical benefit across a wide range of threshold probabilities. In conclusion, the nomogram allows for rapid individualized risk assessment and shows promising potential for clinical translation.