Influence of source and type of admission on in-hospital mortality for coronary artery bypass surgery patients: National results from 1.7 million CABG patients, 1998 to 2002

Background: Hospitals identify the type of coronary artery bypass graft (CABG) surgery admission as routine, urgent, or emergency, and identify CABG admissions as elective, from another hospital, from a long-term healthcare facility, and an admission that results from an emergency room visit. No research has analyzed the importance of these admission characteristics on CABG outcomes. Methods: Using the Nationwide Inpatient Sample data from the Healthcare Cost and Utilization Project database for 1998 through 2002, 1.7 million CABG admissions are analyzed using descriptive and logistic regression techniques to evaluate the extent of differences in in-hospital CABG mortality rates by the type of admission and the source of admission. Results: While there has been 22% decline over our 5-year study period regardless of the source or type of admission, we find that a 2.5-fold difference exists in the in-hospital CABG mortality rates among categories that distinguish the type of admission and the source of admission in the nation's hospital. In 2002, CABG admissions that are routine elective-surgeries have a CABG mortality rate of 1.49%, while urgent CABG admissions from a long-term care facility have an in-hospital mortality rate that is 3.64%. Conclusions: While significant progress has been made lowering in-hospital CABG mortality, sizable differences still remain among the types and sources of CABG admissions. Clinical trial research on CABG patients where the end points include mortality need to be especially mindful of the potential differences and distortions in their data that can be generated due to these various sources of hospital admissions.