Learning and the evolution of medical technologies: the diffusion of coronary angioplasty.

This study uses longitudinal data on patients receiving percutaneous transluminal coronary angioplasty (PTCA) to examine changes in outcomes and costs. All hospitals achieved substantial reductions in inpatient mortality and emergency bypass surgery over time, regardless of the number of procedures performed. Annual hospital procedure volume was also associated with improved outcomes, although the effect is small. There was no evidence that learning by doing (cumulative PTCA volume) influenced outcomes. The high correlation between annual and cumulative procedure volume precludes a point estimate of the effect of learning by doing on costs, although the upper bound on the potential learning effect is sizeable. The results suggest that centralizing provision of PTCA may lead to lower costs, but only small outcomes improvements.