Invasive Cardiology

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The Role of Out-of-Hospital Cardiac Arrest in Predicting Hospital Mortality for Percutaneous Coronary Interventions in the Clinical Outcomes Assessment Program

Author: ^a,bCharles Maynard, PhD, ^cSunil V. Rao, MD, ^dMary Gregg, MD, MHA, ^aRichard C. Phillips, MD, MPH, ^dMark Reisman, MD, ^eEben Tucker, MD, ^eJ. Richard Goss, MD, MPH

ABSTRACT: Published mortality models for percutaneous coronary intervention (PCI), including the Clinical Outcomes Assessment Program (COAP) model, have not considered the effect of out-of-hospital cardiac arrest. The primary objective of this study was to determine if the inclusion of out-of-hospital cardiac arrest altered the COAP mortality model for PCI. The COAP PCI database contains extensive demographic, clinical, procedural and outcome information, including out-of-hospital cardiac arrest, which was added to the data collection form in 2006. This study included 15,586 consecutive PCIs performed in 31 Washington State hospitals in 2006. Using development and test sets, the existing COAP PCI logistic regression mortality model was examined to assess the effect of out-of-hospital arrest on in-hospital mortality. Overall, 2% of individuals undergoing PCI had cardiac arrest prior to hospital arrival. Among 8 hospitals with PCI volumes < 120 cases per year, 4 had cardiac arrest volumes that exceeded 10% of total volume, whereas none of the centers with > 120 cases per year did. In-hospital mortality was 19% in the arrest group and was 1.0% in remaining procedures (p < 0.0001). In the new multivariate model, out-of-hospital cardiac arrest was highly associated with mortality (odds ratio = 5.50; 95% confidence interval [CI] = 3.28–9.25). When evaluated in the test set, the new model had excellent discrimination (c-statistic = 0.89; 95% CI = 0.85–0.93). Out-of-hospital cardiac arrest is an important determinant of risk-adjusted in-hospital mortality for PCI, particularly for hospitals with low volumes and relatively high volumes of cardiac arrest cases.

J INVASIVE CARDIOL 2009; 21:1–5

Over the past 15 years, state and national organizations have devoted considerable effort and resources to measuring hospital and operator performance for percutaneous coronary interventions (PCI).1–10 One of these organizations, the Clinical Outcomes Assessment Program (COAP), measures performance as part of a collaborative quality improvement program for hospitals performing cardiac revascularization procedures in Washington State. Published mortality models for PCI, including the COAP model, have not considered the effect of out-of-hospital cardiac arrest. There is minimal information about the use of PCI in patients with out-of-hospital cardiac arrest, and most of it is from descriptive studies conducted outside the United States.11–14

Since several of the 31 participating COAP hospitals have relatively high proportions of patients with out-of-hospital cardiac arrest, application of available risk stratification models could potentially penalize these sites by underestimating their expected mortality rates. With this in mind, the purpose of this study was to: 1) determine in COAP the proportion of cases with out-of-hospital cardiac arrest; 2) compare baseline and procedural characteristics as well as hospital mortality in cases with and without the condition; and 3) assess whether out-of-hospital cardiac arrest added to the predictive power of the COAP mortality model for PCI.10