External validation of models and simple scoring systems to predict miscarriage in intrauterine pregnancies of uncertain viability

main results and the role of chance: Of the 575 women who were recruited, first trimester outcome was known for 89.2% (n ¼ 513). The model could only be validated in 400 patients, due to missing values in model variables and outcome. The model predicted viability with an area under the ROC curve (AUC) of 0.845 [95% confidence interval (CI), 0.806–0.884] compared with 0.774 (95% CI, 0.701–0.848) in the original study. The AUC for the scoring system was 0.832 (95% CI, 0.792– 0.872) compared with 0.771 (95% CI, 0.698–0.844) from the original study data set. The new model and the scoring system, excluding gestational age, could be evaluated on 503 patients and resulted in an AUC of 0.801 (95% CI, 0.765–0.841) for the model and 0.773 (95% CI, 0.733 –0.812) for the scoring system. limitations,reasonsforcaution: Approximately 22% of patients could not be validated due to missing variables and for 11% of patients the first trimester outcome was unknown. wider implications of the findings: Both the model and the scoring system showed excellent performance on external validation confirming their generalizability and utility in prediction of viability beyond the first trimester in clinical practice. An advantage of the mathematical models original Mo and new Mn and scoring systems original SSo and new SSn is that they can provide women with an individualized