Validation of the prediction model for success of vaginal birth after cesarean delivery at the university hospital in Barcelona

Objective: To validate the prediction model for successful vaginal birth after cesarean delivery (VBAC) based on variables easily obtainable at the first antenatal visit, in a Spanish population. Methods: Retrospective observational study. Women with a single live fetus in cephalic presentation with one previous low-transverse CD who underwent trial of labor after cesarean delivery (TOLAC) at >= 37 gestational weeks between January 2011 and December 2015 were identified in the hospital's information system. Their antenatal medical records and delivery summary reports were reviewed and individual probabilities of successful VBAC were calculated, according to a previously published model. These probabilities were categorized into deciles. For calibration, each decile of predicted probabilities was compared to the observed rates. To assess the accuracy of the prediction model, receiver operating characteristic curve was constructed and the area under the curve (AUC) was calculated. Results: In total, 630 women who underwent TOLAC had all required information and were included in the study. Among them, 450 (71.4%) women had successful VBAC. The AUC was 0.70 (95% confidence interval 0.66-0.74). Conclusion: Prediction ability of the validated model was in agreement with the original study.