Implementation of evidence-based treatments for patients with acute myocardial infarction saves lives, but hospitals show substantial variation in the extent to which they apply these treatments, according to a study of more than 60,000 patients treated at 72 Swedish hospitals during 1996-2007.
During the period studied, Swedish hospitals increasingly used proven treatments for patients presenting with ST-elevation MIs, including increased use of reperfusion therapies, aspirin, clopidogrel, statins, beta-blockers, and ACE inhibitors or angiotensin receptor blockers. Concurrently with increased use of these interventions, the standardized, 1-year mortality of patients dropped from 19% in 1996 to 11% in 2007, Dr. Tomas Jernberg, a cardiologist at Karolinska University Hospital in Stockholm, and his associates reported in an article published online on April 27 (JAMA 2011;305:1677-84).
But in addition to documenting the efficacy of evidence-based therapies for treating acute STEMI, the findings also revealed a wide variation in the application of these therapies by all 72 Swedish hospitals that provide care for patients with acute cardiac diseases.
For example, in 2007, 61% of STEMI patients in Sweden underwent primary percutaneous coronary intervention (PCI), up from 12% in 1996. But in 2007, the 95% confidence interval for hospitals delivering primary PCI was 45%-77%, meaning that 2.5% of the participating Swedish hospitals delivered primary PCI to fewer than 45% of their patients, while the 2.5% of Swedish hospitals that used primary PCI most often delivered it to more than 77% of their STEMI patients.
For several treatments, hospital-to-hospital variation in implementation decreased substantially over the period studied, so that by 2007 most hospitals used the treatment to about the same extent. For example, no hospital prescribed clopidogrel to these patients in 1996 (the drug was approved in Europe in 1998), but its use rose to 82% by 2007. Initially, hospitals showed a wide variability in the introduction of clopidogrel, which peaked in 2002, when a 40% gap separated the top quarter of prescribing hospitals from the bottom quarter. But during 2003-2007, this gap shrank, and by 2007 the difference in prescribing rates between the top and bottom hospital quartiles stood at only 3.4%.
However, variations in the prescribing of ACE inhibitors or ARBs persisted through 2007, "indicating a continuous uncertainty around the indications for these treatments early after ST-elevation MI," the authors wrote. By 2007, about 70% of these patients began receiving an ACE inhibitor or ARB at their hospital discharge, but the percentage varied from as low as 50% at some hospitals to as high as 80% at others.
"Our study demonstrates a large variation in the implementation of new treatments between different hospitals. These large variations, especially regarding coronary angiography during the hospital stay and subsequent dual antiplatelet therapy, were greatest during the start-up of new treatment modalities, likely reflecting differential rates of adoption of new treatments and decreased gradually over time," the authors said. They highlighted this variability and its reduction over time as a key factor in improved patient outcomes.
"Variation in treatment and deviations from guideline recommendations have negative effects on mortality and morbidity. The gradual reduction in variability leading to a high level of guideline adherence might therefore be a key reason for the reduction in mortality" seen during 1996-2007. "Therefore, identification of undue variations in the processes of care and highlighting areas of need for quality improvement programs are important tasks for the quality registries in health care," they concluded.
Dr. Jernberg and his coauthors said that they had no disclosures.