Impact of Volume and Temporal Distance on the Value of Organ Transplant Surgery

描述（由申请人提供）：在外科手术（包括器官移植）中，提供者数量与患者预后之间的关系得到了很好的研究。器官移植的证据是有限的，很大程度上是相关的。获得体积对移植结果的合理因果影响对管理和政策决策很重要。此外，手术中的时间距离，即医生完成特定手术的时间间隔，已被证明与较差的患者预后呈正相关。具体来说，当他们的医生上次进行手术的时间增加时，患者的情况会更糟。这种效应尚未在移植中进行研究。我们将研究肾脏、肝脏和胰腺移植以解决多重目标，采用2009-2011年移植接受者科学登记处的数据。首先，我们将使用计量经济学方法来检验中心体积和时间距离对患者预后的相对影响，这些方法旨在对这些影响产生合理的因果估计，而不仅仅是统计关联。我们将采用中心固定效应回归建模技术来检验体积和时间距离效应。然后，我们建议使用现有的半参数风险建模技术，允许通过数值积分技术来解释未观察到的异质性。其次，我们将研究体积或时间距离是否会影响资源使用。器官是一种稀缺资源，移植手术的质量直接影响移植市场的效率。这种质量和资源使用的检查将为评估中心为患者提供的价值提供一个框架。此外，一旦确定了数量和时间距离效应的大小，这些信息可用于直接通知移植中心的认证政策和干预措施，以维持移植中心的组织人力资本。

DESCRIPTION (provided by applicant): There is a well investigated association between provider volume and patient outcomes in surgery, including organ transplantation. The evidence in organ transplantation is limited and largely correlative. Obtaining plausibly causal impacts of volume on outcomes in transplantation is important for managerial and policy decision making. In addition, temporal distance in surgery, which is defined as the time between a provider's performances of a particular procedure, has been shown to be positively related to poorer patient outcomes. Specifically, patients do worse when the time since their provider last performed the procedure increases. This effect has not been investigated in transplantation. We will examine the kidney, liver and pancreas transplants to address multiple aims, employing data from the Scientific Registry of Transplant Recipients for the years 2009-2011. First, we will examine the relative impact of center volume and temporal distance on patient outcomes both proximal to the procedure in time and over the longer horizon using econometric methods designed to yield plausibly causal estimates of these effects rather than only statistical associations. We will employ center fixed effects regression modeling techniques to examine volume and temporal distance effects. We then propose to use existing semi-parametric hazard modeling techniques that allow the unobserved heterogeneity to be accounted for through numerical integration techniques. Second, we will examine whether volume or temporal distance impacts resource use. Organs are a scarce resource, and as such the quality of the transplant surgery impacts the efficiency of the transplant market. Together this examination of quality and resource use will provide a framework for assessing the value the centers provide for patients. Furthermore, once the magnitudes of the volume and temporal distance effects are identified, this information can be used to directly inform transplant center certification policie and interventions to maintain the organization human capital of the transplant centers.