The relation between patients' outcomes and the volume of cardioverter-defibrillator implantation procedures performed by physicians treating medicare beneficiaries

OBJECTIVES The purpose of this study is to determine if implantable cardioverter-defibrillator (ICD) implantation should be limited to physicians with high procedural volume. BACKGROUND Expanding indications for ICDs will result in an increasing number of physicians implanting these devices. METHODS Using the 20% Part B Medicare files for 1999 through 2001, we identified new ICD implantations and the corresponding denominator files. We used Medicare Provider Analysis and Review hospital records and the appropriate International Classification of Diseases-9 diagnosis and procedure codes to define complications within 90 days. We defined physician volume categories by assigning one-quarter of the patients to each quartile. A logistic regression model was used to adjust outcomes for potential confounders. RESULTS Ninety-day mortality did not differ between patients who had their ICD implanted by physicians with the highest volume of implants and those who had their ICD implanted by physicians with the lowest volume of implants (6.2% vs. 5.9%, odds ratio [OR] 0.99; 95% confidence interval [CI] 0.75 to 1.30). Within 90 days, mechanical complications were significantly higher in the lowest volume quartile (OR 1.47; 95% CI 1.09 to 1.99) but were comparable for physicians who implanted at least 11 ICDs per year. The risk of ICD infection was significantly higher in patients who had their ICD implanted by physicians with the lowest volume of implants (OR 2.47; 95% CI 1.18 to 5.17). CONCLUSIONS We observed an association between a higher volume of ICD implants and a lower rate of mechanical complications and infections. This association suggests that ICD implantation should not be performed by physicians without regard to their procedural volume.