Understanding causal pathways within health systems policy evaluation through mediation analysis: an application to payment for performance (P4P) in Tanzania.
Understanding causal pathways within health systems policy evaluation through mediation analysis: an application to payment for performance (P4P) in Tanzania.
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DOI：
10.1186/s13012-016-0540-1
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发表时间：
2017-02-02
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影响因子：
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通讯作者：
Borghi J
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文献类型：
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作者：
Anselmi L;Binyaruka P;Borghi J
对按业绩付费方案的评价主要侧重于了解对保健服务覆盖面的贡献，而没有分析因果机制。本文的总体目标是测试因果关系的途径，通过P4P计划可能（或可能不会）影响孕产妇保健的结果。我们使用的数据来自对坦桑尼亚P4P项目的评估。2012年1月和2013年2月，从坦桑尼亚7个干预区和4个比较区的150个卫生设施的3000名妇女和200名卫生工作者中收集了数据。我们应用因果中介分析，使用线性结构方程模型，以确定直接和间接的影响，P4P的机构交付率和摄取的两个剂量的抗疟药物在怀孕期间。我们首先运行了一系列线性差中差回归模型来测试P4P对潜在介质的影响，然后我们将其纳入线性差中差模型，以评估P4P对结果的影响。我们使用半参数方法测试了我们的结果对未测量混杂的鲁棒性。P4P降低了妇女支付分娩护理费用的可能性（-4.5个百分点），这是P4P对机构分娩（48%）和公共卫生设施分娩（78%）的总体影响的中介。P4P降低了一些基本药物的缺货率，特别是催产素（-36个百分点），这介导了P4P对机构分娩（22%）和公共卫生设施分娩（30%）的总体影响。P4P增加了分娩时的善意（5个百分点），这介导了P4P对机构分娩（48%）和公共卫生设施分娩（49%）的影响。P4P增加了在过去90天内进行监督访问的可能性（18个百分点），这介导了产前护理期间两种抗疟剂量（IPT 2）吸收的P4P总效应的15%。在分娩过程中的善良和支付分娩护理的可能性是最强大的中介不可测量的混杂。P4P对住院分娩的影响是由融资和人力资源因素介导的，而妊娠期间抗疟药物的服用则是由治理因素介导的。需要进一步的研究来探索更多和更复杂的因果关系。
The evaluation of payment for performance (P4P) programmes has focused mainly on understanding contributions to health service coverage, without unpacking causal mechanisms. The overall aim of the paper is to test the causal pathways through which P4P schemes may (or may not) influence maternal care outcomes. We used data from an evaluation of a P4P programme in Tanzania. Data were collected from a sample of 3000 women who delivered in the 12 months prior to interview and 200 health workers at 150 health facilities from seven intervention and four comparison districts in Tanzania in January 2012 and in February 2013. We applied causal mediation analysis using a linear structural equation model to identify direct and indirect effects of P4P on institutional delivery rates and on the uptake of two doses of an antimalarial drug during pregnancy. We first ran a series of linear difference-in-difference regression models to test the effect of P4P on potential mediators, which we then included in a linear difference-in-difference model evaluating the impact of P4P on the outcome. We tested the robustness of our results to unmeasured confounding using semi-parametric methods. P4P reduced the probability of women paying for delivery care (−4.5 percentage points) which mediates the total effect of P4P on institutional deliveries (by 48%) and on deliveries in a public health facility (by 78%). P4P reduced the stock-out rate for some essential drugs, specifically oxytocin (−36 percentage points), which mediated the total effect of P4P on institutional deliveries (by 22%) and deliveries in a public health facility (by 30%). P4P increased kindness at delivery (5 percentage points), which mediated the effect of P4P on institutional deliveries (by 48%) and on deliveries in a public health facility (by 49%). P4P increased the likelihood of supervision visits taking place within the last 90 days (18 percentage points), which mediated 15% of the total P4P effect on the uptake of two antimalarial doses during antenatal care (IPT2). Kindness during deliveries and the probability of paying out of pocket for delivery care were the mediators most robust to unmeasured confounding. The effect of P4P on institutional deliveries is mediated by financing and human resources factors, while uptake of antimalarials in pregnancy is mediated by governance factors. Further research is required to explore additional and more complex causal pathways.