In Reply. —We appreciate the updated information provided by Dr Phillips and colleagues 1 concerning the results of their multivariate-adjusted analyses. Their report lends further support to the procedure volume—complication relationship for percutaneous ballon angioplasty procedures. We agree that their use of administrative data did not allow for adjustment for the range of clinical variables available in our study. Nonetheless, it is interesting that, similar to our findings, Phillips and colleagues found that centers with higher procedure volume (in their study, >500 PTCAs) had significantly lower than predicted adverse outcomes for patients without a principal diagnosis of AMI. The fact that their results for hospitals performing fewer than 200 PTCAs per year differed from ours certainly could have been attributable to differences in the source of hospitals used in these studies, differences in outcome definitions, or even differences in the effects of geographical and health care market forces on the