CLINICIAN ACCURACY IN PREDICTING SUCCESSFUL VAGINAL BIRTH AFTER CESAREAN: IMPACT OF PATIENT CHARACTERISTICS ON PROVIDER COUNSELING

Purpose: To understand the determinants and accuracy of provider prediction of successful trial of labor after cesarean (TOLAC).

Methods: Cross-sectional, questionnaire-based study of OB/GYN providers (n=125).  Eight clinical vignettes were presented and providers asked how they would counsel such a patient about TOLAC.  Paired clinical scenarios were utilized to compare provider-predicted vaginal birth after cesarean (VBAC) rates based on individual patient characteristics; accuracy was assessed using predictions from the NICHD VBAC calculator as a reference.  An accurate estimate was defined as one within 5% of the 95% confidence interval of success predicted by the calculator.

Results: Estimated likelihood of successful TOLAC ranged from 0% to 99% (mean 69%).  93% of respondents stated that they alter their prediction of successful VBAC based on clinical characteristics, which was confirmed by clinical patient scenario responses.  Non-recurrent indication (74% vs 59%), prior VBAC (79% vs 69%), AMA (74% vs. 69%), elevated BMI (74% vs 67%), and history of two prior cesareans (74% vs 60%,) significantly affected predicted likelihood of success (p<0.01 for all); race did not. Compared to the NICHD VBAC calculator, with the exception of one scenario with a nonrecurring indication for the prior cesarean, the majority of respondents were not accurate in assessing the likelihood of successful VBAC in a variety of clinical situations.  However, more than 90% of respondents would offer TOLAC in all clinical scenarios with one prior Cesarean delivery regardless of their prediction of success. Only 70% would offer TOLAC if a patient had 2 prior Cesarean deliveries, and willingness to offer TOLAC decreased if induction of labor was required.  62% of providers surveyed felt they were “adequately” trained to counsel patients regarding TOLAC; physicians in training were more likely to feel that they were not adequately trained.    

Conclusions: Providers individualize counseling regarding TOLAC based on clinical characteristics, but are generally inaccurate in their predictions of the likelihood of success when the impact of multiple characteristics must be integrated.  Only 62% of respondents felt adequately trained to counsel patients regarding TOLAC and estimates of likelihood of success as well as uterine rupture varied widely. Given the priority that patients place on provider counseling for shared decision making in this context, this suggests an opportunity for additional provider education and decision support to optimize counseling.