AMI Mortality Rates in US Improved Over Decade

August 19, 2009—A study published by Harlan M. Krumholz, MD, et al in the Journal of the American Medical Association, showed a reduction in acute myocardial infarction (AMI) mortality in the United States from 1995 to 2006 (2009;302:767–773).

According to the investigators, during the last 2 decades, health care professional, consumer, and payer organizations have sought to improve outcomes for patients hospitalized with AMI. However, little has been reported about improvements in hospital short-term mortality rates or reductions in between-hospital variation in short-term mortality rates.

The objective of this study was to estimate hospital-level, 30-day, risk-standardized mortality rates (RSMRs) for patients discharged with AMI. This was an observational study using administrative data and a validated risk model to evaluate 3,195,672 discharges in 2,755,370 patients discharged from nonfederal acute-care hospitals in the United States between January 1, 1995, and December 31, 2006. Patients were 65 years or older (mean, 78 years) and had at least a 12-month history of fee-for-service enrollment before the index hospitalization. Patients discharged within 1 day of an admission not against medical advice were excluded because it is unlikely that these patients had sustained an AMI. The main outcome measure was hospital-specific, 30-day, all-cause RSMR.

The investigators reported that at the patient level, the odds of dying within 30 days of admission if treated at a hospital one standard deviation above the national average relative to that if treated at a hospital one standard deviation below the national average were 1.63 (95% confidence interval [CI], 1.60–1.65) in 1995 and 1.56 (95% CI, 1.53–1.60) in 2006. In terms of hospital-specific RSMRs, a decrease from 18.8% in 1995 to 15.8% in 2006 was observed (odds ratio, 0.76; 95% CI, 0.75–0.77). A reduction in between-hospital heterogeneity in the RSMRs was also observed: the coefficient of variation decreased from 11.2% to 10.8%, the interquartile range decreased from 2.8% to 2.1%, and the between-hospital variance decreased from 4.4% to 2.9%. The investigators concluded that between 1995 and 2006, the RSMR for Medicare patients discharged with AMI showed a significant decrease, as did between-hospital variation.

The Society of Cardiovascular and Angiographic Interventions (SCAI) commented that this study is a testament to the continued increase in quality patient care and expanded treatment options driven by medical innovation. Advances in standards of care, such as the door-to-balloon initiative to treat heart attack patients in 90 minutes or less, and treatment options including angioplasty and drug-eluting stents, have helped save lives and improved the quality of life for countless heart disease patients, many of whom may have had little hope for survival just 20 years ago. These gains overlap with significant growth in the number of hospitals in the United States equipped with cardiac catheterization labs, from 22% in 1998 to 30% in 2005 and an increase in the number of patients undergoing interventional procedures such as angioplasty and stenting. Clearly, quick access to interventional cardiology procedures is essential to continuing this trend toward reduced mortality. SCAI emphasized the need for ongoing efforts to continue to improve heart disease outcomes and cultivate medical innovation, particularly in light of the current health care reform debate.

"The significant advances we've seen in heart attack care, including angioplasty and the door-to-balloon initiative to treat heart attack patients more quickly, are true success stories of modern medicine," commented SCAI President Steven R. Bailey, MD. "While advances in cardiovascular care have helped save countless lives in the past decade, heart disease remains the number one killer in America. With an increased focus on health reform, it's vitally important we continue to provide innovative treatment options to save lives and improve the quality of life for heart disease patients."