Edward Norton

Explaining Variation in Mortality after Pediatric Cardiac Surgery

Research Project Description
Michael Gaies, Mousumi Banerjee, Edward Norton, Justin B. Dimick, Sara Kate Pasquali

Congenital heart defects are the most common birth defect in the U.S. Over 20,000 children require complex cardiac surgery for tetralogy of Fallot, transposition of the great arteries, and single ventricle heart disease among other conditions. Despite advances in surgical technique and perioperative care, surgical mortality for these children remains high, with rates approaching 25% for more complex procedures like the Norwood operation. Furthermore, wide variation in mortality exists across centers, suggesting opportunities for substantial improvement.
How best to reduce variation and improve outcomes in pediatric cardiac surgery remains unclear, however. For adults undergoing complex surgery, operative mortality has declined significantly over the last decade. Although the reasons for improvement are likely multifactorial, many credit seminal research efforts to elucidate the clinical epidemiology of perioperative mortality as a crucial first step towards understanding outcome variation. Moreover, these landmark studies have focused further research efforts to delineate the structures and processes that underlie variation. In contrast, for pediatric cardiac surgical patients these mechanisms have been largely unexplored. The epidemiology of complications and death after pediatric cardiac surgery has not been well-established. As well, resource availability in the intensive care units and general post-operative wards have not been rigorously examined and related to outcomes. Finally, the impact of perioperative patient-level care processes on complication rates, response to complications, and overall mortality has not been determined.
In this context, we will take advantage of a unique collaborative ? the Pediatric Cardiac Critical Care Consortium (PC4) ? to investigate the mechanisms of variation in mortality after pediatric cardiac surgery. PC4 is an international, multi-institutional consortium of pediatric cardiac intensive care units, led by the applicant, maintaining a database rich with clinical outcome data as well as process of care variables, and partners with other clinical registries to share data elements. Our proposal has 3 specific aims:

Aim 1. To determine the clinical epidemiology of mortality after pediatric cardiac surgery.
Based on in-depth analysis of consecutive mortalities at PC4 institutions, we will explore a conceptual model of perioperative mortality, and determine the incidence and chronology of complications causing perioperative mortality after pediatric cardiac surgery. We will then assess the association between specific complications, cause-specific mortality rates and center-specific adjusted mortality. We hypothesize that acute heart failure (or low cardiac output syndrome) will be the seminal complication in the majority of deaths, and that a center?s ability to prevent or treat this complication will determine overall hospital performance.

Aim 2. To identify structural and organizational factors associated with pediatric cardiac surgical outcomes.
Focusing on the units where post-operative care takes place, we will assess the importance of system factors in explaining variation in surgical outcomes. We will concentrate particularly on those that might thought to be related to the seminal complications identified in Aim 1. Post-operative care unit factors most likely related to recognition and response to complications such as intensivist and nurse staffing, cardiac rapid response services, and availability of specialized ancillary services will be compared between high- and low-performing centers within PC4. We hypothesize that unit and physician specialization, and staffing patterns will associate with hospital performance.

Aim 3. To explore specific processes of care associated with improved outcomes.
Again informed by our findings from Aim 1, we will create and implement a specific module within the PC4 registry to assess specific post-operative care practices likely as

National Heart, Lung, And Blood Institute
(1 K08 HL 116639 01 A1)

Funding Period: 4/1/2014 to 1/31/2019

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