Coronary angioplasty volume-outcome relationships for hospitals and cardiologists

Objective.-To assess the relationship between each of 2 provider volume measures (annual hospital volume and annual cardiologist volume) for percutaneous transluminal coronary angioplasty (PTCA) and 2 outcomes of PTCA (in-hospital mortality and same-stay coronary artery bypass graft [CABG] surgery). Design.-Cohort study, using data from January 1, 1991, through December 31, 1994, from the Coronary Angioplasty Reporting System of the New York State Department of Health. Setting.-Thirty-one hospitals in New York State in which PTCA was performed during 1991-1994. Patients.-All 62 670 patients discharged after undergoing PTCA in these hospitals during 1991-1994. Main Outcome Measures.-Rates of in-hospital mortality and CABG surgery during the same stay as the PTCA. Results.-The overall in-hospital mortality rate for patients undergoing PTCA in New York during 1991-1994 was 0.90%, and the same-stay CABG surgery rate was 3.43%. Patients undergoing PTCA in hospitals with annual PTCA volumes less than 600 experienced a significantly higher risk-adjusted in-hospital mortality rate of 0.96% (95% confidence interval [CI], 0.91%-1.01%) and risk-adjusted same-stay CABG surgery rate of 3.92% (95% CI, 3.76%-4.08%). Patients undergoing PTCA by cardiologists with annual PTCA volumes less than 75 had mortality rates of 1.03% (95% CI, 0.91%-1.17%) and same-stay CABG surgery rates of 3.93% (95% CI, 3.65%-4.24%); both of these rates were also significantly higher than the rates for all patients. Also, same-stay CABG surgery rates for patients undergoing PTCA in hospitals with annual volumes of 600 to 999 performed by cardiologists with annual volumes of 75 to 174 (2.99%; 95% CI, 2.69%-3.31%) and 175 or more (2.84%; 95% CI, 2.57%-3.14%) were significantly lower than the overall statewide rate (3.43%). Conclusions.-In New York State, both hospital PTCA volume and cardiologist PTCA volume are significantly inversely related to in-hospital mortality rate and same-stay CABG surgery rate for patients undergoing PTCA.