From the Departments of Obstetrics and Gynecology, the University of Texas Medical Branch, Galveston, Texas; the University of Texas Health Science Center, Houston, Texas; and Northwestern University Feinberg School of Medicine, Chicago, Illinois.
Obstet Gynecol. 2009 Nov;114(5):1029-1033. doi: 10.1097/AOG.0b013e3181bb0dde.
To validate a previously developed vaginal birth after cesarean (VBAC) prediction model using a patient cohort different than that from which it was derived.
We performed a cohort study of all term pregnant women (January 2002-August 2007) with one prior low transverse cesarean delivery attempting a trial of labor. Variables used in the final prediction model (maternal age, prepregnancy body mass index, ethnicity, prior vaginal delivery, prior VBAC, and indication for prior cesarean delivery) were extracted from medical records and used to calculate an individual woman's predicted VBAC success rate. These rates at the level of the study population then were partitioned into deciles and compared with the actual VBAC rates.
Of 545 women who fit the inclusion criteria, 502 had complete data available. A total of 262 (52.2%) had VBAC. The predicted probability of VBAC, as calculated by the regression equation, was significantly higher in those who had a successful trial of labor (median 78.4%, interquartile range 62.1-88.2) than in those who did not (median 59.7%, interquartile range 50.8-75.3, P<.001). The predictive model had an area under the receiver operating characteristic of 0.70 (95% confidence interval 0.65-0.74, P<.001), which was similar to that originally described. The actual VBAC rates did not differ from the predicted rates when the predicted chance of success was less than 50%. Above a 50% predicted success, the achieved success rates were consistently 10-20% lower.
The published nomogram is predictive of VBAC success. It may help pregnant women contemplating a trial of labor reach a more informed decision.
II.
使用不同于原始数据的患者队列验证先前开发的剖宫产后阴道分娩（VBAC）预测模型。
我们对所有足月妊娠（2002 年 1 月至 2007 年 8 月）且有一次既往横行剖宫产史尝试试产的妇女进行了队列研究。最终预测模型中使用的变量（产妇年龄、孕前体重指数、种族、既往阴道分娩史、既往 VBAC 史和既往剖宫产指征）从病历中提取，并用于计算每位女性的预测 VBAC 成功率。然后，将研究人群的这些比率分为十等份，并与实际 VBAC 率进行比较。
符合纳入标准的 545 名妇女中，有 502 名有完整的数据。共有 262 名（52.2%）产妇 VBAC 成功。根据回归方程计算的 VBAC 预测概率在试产成功的妇女中明显更高（中位数为 78.4%，四分位间距为 62.1%-88.2%），而在试产失败的妇女中则更低（中位数为 59.7%，四分位间距为 50.8%-75.3%，P<.001）。预测模型的受试者工作特征曲线下面积为 0.70（95%置信区间 0.65-0.74，P<.001），与最初描述的相似。当预测成功率小于 50%时，实际 VBAC 率与预测率没有差异。在预测成功率大于 50%时，实际成功率始终低 10%-20%。
已发表的列线图可预测 VBAC 的成功率。它可以帮助考虑试产的孕妇做出更明智的决策。
II 级。
