500: Clinical prediction modeling for vaginal delivery after induction of labor in pregnancy-related hypertensive disorders

Abstract

To identify characteristics associated with vaginal delivery compared to cesarean delivery after labor induction among women with pregnancy-related hypertensive disorders and develop and validate a prediction model to assist in clinical care. We created a retrospective cohort of women who were induced with a diagnosis of a hypertensive disorder of pregnancy and had a singleton live born infant at >34 weeks’ gestation at Women & Infants Hospital of Rhode Island between January 2002 and March 2014. Exclusion criteria included spontaneous labor, planned cesarean delivery, and known fetal anomalies. The study cohort was randomly divided into two groups; 70% of pregnancies were used to develop the prediction model and 30% were used to validate the model. Candidate predictors were limited to those with biologic plausibility to affect induction success and to those that are reliably available to a practitioner at time of induction. Stepwise backward logistic regression was used to build the most parsimonious model. Hosmer-Lemeshow test was used to demonstrate goodness-of-fit. Model discrimination was evaluated via concordance index and displayed via area under the receiver operator curve (AUC). The developed model was internally validated using the remaining 30% of the cohort to further assess predictive ability. Of the 1,357 women meeting study criteria, 974 (71.8%) had a vaginal delivery following induction. The final model consisted of eight variables, which were significantly associated with mode of delivery following induction, including maternal age, BMI, gestational age, intrapartum magnesium sulfate, need for cervical ripening, prior cesarean delivery, cervical dilation and effacement. Model calibration and discrimination were satisfactory with Hosmer-Lemeshow test p=0.35 and an AUC (95% CI) of 0.76 (0.73, 0.79). Internal validation demonstrated similar discriminatory ability. Using information available prior to labor induction, our model can predict vaginal delivery success for women with hypertensive disorders of pregnancy and may aid in clinical decision-making.View Large Image Figure ViewerDownload Hi-res image Download (PPT)