The effect of high-risk ST elevation myocardial infarction transfer patients on risk-adjusted in-hospital mortality: A report from the American Heart Association Mission: Lifeline program

Background Hospital mortality is an important quality measure for acute myocardial infarction care. There is a concern that despite risk adjustment, percutaneous coronary intervention hospitals accepting a greater volume of high-risk ST elevation myocardial infarction (STEMI) transfer patients may have their reported mortality rates adversely affected. Methods The STEMI patients in the National Cardiovascular Data RegistryAcute Coronary Treatment Intervention Outcomes Network Registry Get With the Guidelines from April 2011 to December 2013 were included. High-risk STEMI was defined as having either cardiogenic shock or cardiac arrest on first medical contact. Receiving hospitals were divided into tertiles based on the ratio of high-risk STEMI transfer patients to the total number of STEMI patients treated at each hospital. Using the Action Coronary Treatment Intervention Outcomes Network Registry Get With the Guidelines in-hospital mortality risk model, we calculated the difference in risk-standardized in-hospital mortality before and after excluding high-risk STEMI transfers in each tertile. Results Among 119,680 STEMI patients treated at 539 receiving hospitals, 37,028 (31 %) were transfer patients, of whom 4,500 (12%) were highrisk. The proportion of high-risk STEMI transfer patients ranged from 0% to 12% across hospitals. Unadjusted mortality rates in the low-, middle-, and high-tertile hospitals were 6.0%, 6.0%, and 5.9% among all STEMI patients and 6.0%, 5.5%, and 4.6% after excluding high-risk STEMI transfers. However, risk-standardized hospital mortality rates were not significantly changed after excluding high-risk STEMI transfer patients in any of the 3 hospital tertiles (low, -0.04%; middle, -0.05%; and high, 0.03%). Conclusions Risk-adjusted in-hospital mortality rates were not adversely affected in STEMI-receiving hospitals who accepted more high-risk STEMI transfer patients when a clinical mortality risk model was used for risk adjustment.