The effect of the use of a decision aid with individual risk estimation on the mode of delivery after a caesarean section: A prospective cohort study

Objective
After one previous caesarean section (CS), pregnant women can deliver by elective repeat CS or have a trial of labor which can end in a vaginal birth after caesarean (VBAC) or an unplanned CS. Despite guidelines describing women’s rights to make an informed choice, trial of labor and VBAC rates vary greatly worldwide. Many women are inadequately informed due to caregivers’ fear of an increase in CS rates in a high VBAC rate setting. We compared counseling with a decision aid (DA) including a prediction model on VBAC to care as usual. We hypothesize that counselling with the DA does not decrease VBAC rates. In addition, we aimed to study the effects on unplanned CS rate, patient involvement in decision-making and elective repeat CS rates.
Methods
We performed a prospective cohort study. From 2012 to 2014, 483 women in six hospitals, where the DA was used (intervention group), were compared with 441 women in six matched hospitals (control group). Women with one previous CS, pregnant of a singleton in cephalic presentation, delivering after 37 weeks 0 days were eligible for inclusion.
Results
There was no significant difference in VBAC rates between the intervention (45%) and control group (46%) (adjusted odds ratio 0,92 (95% Confidence interval 0.69–1.23)). In the intervention group more women (42%) chose an elective repeat CS compared to the control group (31%) (adjusted odds ratio 1.6 (95% Confidence interval 1.18–2.17)). Of women choosing trial of labor, in the intervention group 77% delivered vaginally compared to 67% in the control group, resulting in an unplanned CS adjusted odds ratio of 0,57 (0.40–0.82) in the intervention group. In the intervention group, more women reported to be involved in decision-making (98% vs. 68%, P< 0.001).
Conclusions
Implementing a decision aid with a prediction model for risk selection suggests unchanged VBAC rates, but 40% reduction in unplanned CS rates, increase in elective repeat CS and improved patient involvement in decision-making.

## 研究目的
对于有1次剖宫产（caesarean section, CS）史的孕妇，分娩方式可选择择期重复性剖宫产，或进行试产（trial of labor），试产结局可为剖宫产后阴道分娩（vaginal birth after caesarean, VBAC）或非计划性剖宫产。尽管现有指南明确了孕妇享有知情选择的权利，但全球范围内试产率与VBAC率差异悬殊。在VBAC率较高的医疗环境中，由于医护人员担忧剖宫产率上升，许多孕妇未能获得充分的知情信息。本研究对比了采用包含VBAC预测模型的决策辅助工具（decision aid, DA）的咨询服务与常规护理的效果，假设使用决策辅助工具的咨询不会降低VBAC率。此外，本研究还旨在探讨该干预对非计划性剖宫产率、患者决策参与度及择期重复性剖宫产率的影响。

## 研究方法
本研究为前瞻性队列研究（prospective cohort study）。2012年至2014年间，我们纳入6家使用决策辅助工具的医院的483名孕妇作为干预组，同时纳入6家匹配医院的441名孕妇作为对照组。纳入标准为：有1次剖宫产史、单胎头位、孕周≥37周0天的孕妇。

## 研究结果
干预组与对照组的VBAC率无显著差异（干预组45%，对照组46%；校正比值比（adjusted odds ratio）0.92，95%置信区间（confidence interval, CI）0.69–1.23）。干预组中选择择期重复性剖宫产的孕妇比例（42%）高于对照组（31%；校正比值比1.6，95%置信区间1.18–2.17）。在选择试产的孕妇中，干预组阴道分娩率为77%，高于对照组的67%；干预组的非计划性剖宫产校正比值比为0.57（95%置信区间0.40–0.82）。此外，干预组报告参与决策的孕妇比例更高（98% vs. 68%，P< 0.001）。

## 研究结论
采用包含风险预测模型的决策辅助工具，可使VBAC率保持稳定，但可使非计划性剖宫产率降低40%，提升择期重复性剖宫产的选择比例，并改善患者的决策参与度。