Volume-outcome relationship for coronary artery bypass grafting in an era of decreasing volume

Area of Science:

• Cardiovascular Surgery
• Health Services Research
• Public Health

Background:

• Coronary artery bypass grafting (CABG) is a major cardiac procedure.
• Concerns exist regarding the impact of decreasing procedure volumes on patient outcomes.
• Hospital volume has been proposed as a predictor of surgical success.

Purpose of the Study:

• To investigate the relationship between changes in CABG procedure volume and in-hospital mortality rates.
• To determine if a reduction in CABG volume correlates with an increase in mortality.
• To evaluate the predictive value of procedure volume for patient outcomes.

Main Methods:

• Analysis of a 20% random sample of US hospital discharge data from 1988 to 2003 (Nationwide Inpatient Sample).
• Inclusion of all patients undergoing CABG or percutaneous transluminal coronary interventions.
• Assessment of cardiac procedure rates, hospital volume categories, and CABG mortality rates.

Main Results:

• CABG rates increased until 1997, then declined by 2003, while percutaneous interventions tripled.
• The proportion of high-volume CABG hospitals decreased significantly from 1997 to 2003.
• Despite declining CABG volume, the in-hospital mortality rate steadily decreased from 5.4% to 3.3% over the study period.

Conclusions:

• CABG volume has decreased since 1997, coinciding with a reduction in in-hospital mortality.
• Reduced CABG volume is associated with lower mortality, a counterintuitive finding.
• Procedure volume alone may be an insufficient predictor for healthcare regionalization strategies.