The relationship between the emergent primary percutaneous coronary intervention quality measure and inpatient myocardial infarction mortality

Abstract

Background: In the setting of acute ST-segment elevation myocardial infarction (STEMI), reperfusion therapy with emergent primary percutaneous coronary intervention (PCI) significantly reduces mortality. It is unknown whether a hospital's performance on the Centers for Medicare & Medicaid Services (CMS) quality metric for time from patient arrival to angioplasty is associated with its overall hospital acute myocardial infarction (AMI) mortality rate.

Objectives: The objective of this study was to evaluate if hospitals with higher performance on the time-to-PCI quality measure are more likely to achieve lower mortality for patients admitted for any type of AMI.

Methods: Using merged 2006 data from the Nationwide Inpatient Sample (NIS), the American Hospital Association (AHA) annual survey, and CMS Hospital Compare quality indicator data, we examined 69,101 admissions with an International Classification of Diseases, Ninth Revision (ICD-9)-coded principal diagnosis of AMI in the 116 hospitals that reported more than 24 emergent primary PCI admissions in that year. Hospitals were categorized into quartiles according to percentage of admissions in 2006 that achieved the primary PCI timeliness threshold (time-to-PCI quality measure). Using a random effects logistic regression model of inpatient mortality, we examined the significance of the hospital time-to-PCI quality measure after adjustment for other hospital and individual patient sociodemographic and clinical characteristics.

Results: The unadjusted inpatient AMI mortality rate at the 27 top quartile hospitals was 4.3%, compared to 5.1% at the 32 bottom quartile (worst performing) hospitals. The risk-adjusted odds ratio (OR) of inpatient death was 0.83 (95% confidence interval [CI] = 0.72 to 0.95), or 17% lower odds of inpatient death, among patients admitted to hospitals in the top quartile for the time-to-PCI quality measure compared to the case if the hospitals were in the bottom 25th percentile.

Conclusions: Hospitals with the highest and second highest quartiles of time-to-PCI quality measure had a significantly lower overall AMI mortality rate than the lowest quartile hospitals. Despite the fact that a minority of all patients with AMI get an emergent primary PCI, hospitals that perform this more efficiently also had a significantly lower mortality rate for all their patients admitted with AMI. The time-to-PCI quality measure in 2006 was a potentially important proxy measure for overall AMI quality of care.

Figure 1

Admission Sample Selection. NIS = National Inpatient Sample; AMI = Acute Myocardial Infarction; PCI = Percutaneous Catheterization Intervention.

Figure 2

Scatter Plot Illustrating Unadjusted AMI Inpatient Mortality Rate as Function of Each Hospital’s Time-to-PCI Quality Measure Score