Evolution of the volume-outcome relation for hospitals performing coronary angioplasty

Area of Science:

• Cardiovascular Surgery
• Health Services Research
• Medical Quality Improvement

Background:

• Higher surgical procedure volumes in hospitals are generally associated with better patient outcomes.
• This study investigates the historical trends of the volume-outcome relationship in healthcare.

Purpose of the Study:

• To examine the evolution of the volume-outcome relationship for percutaneous transluminal coronary angioplasty (PTCA) procedures over time.
• To assess changes in in-hospital mortality and bypass surgery rates based on hospital PTCA volume across different time periods.

Main Methods:

• Analysis of 353,488 patient cases treated in California between 1984 and 1996.
• Utilized descriptive statistics and logistic regression to compare outcomes across three distinct time intervals: 1984-1987, 1988-1992, and 1993-1996.
• Examined in-hospital mortality and bypass surgery rates in relation to hospital PTCA procedure volume (<200 vs. >400 procedures/year).

Main Results:

• In-hospital mortality for low-volume (<200 PTCA/year) vs. high-volume (>400 PTCA/year) hospitals decreased from 2.5% vs. 1.3% (1984-1987) to 1.7% vs. 1.3% (1993-1996).
• Bypass surgery rates narrowed and decreased in low-volume vs. high-volume hospitals, from 12.4% vs. 6.9% to 4.6% vs. 3.3% over the study period.
• PTCA volume significantly predicted mortality and bypass rates, with outcome improvements in low-volume hospitals comparable to benefits seen in high-volume centers.

Conclusions:

• The disparity in outcomes between low- and high-volume hospitals for PTCA has significantly narrowed over time.
• All hospitals demonstrated substantial improvements in patient outcomes, irrespective of initial volume.
• Lower minimum volume standards for PTCA may be appropriate in underserved areas where angioplasty is otherwise unavailable.