Regional variation in carotid artery stenting and endarterectomy in the Medicare population.

BACKGROUND: To describe geographic variation in population-based rates of carotid artery stenting (CAS) and carotid endarterectomy (CEA) performed in Medicare beneficiaries. METHODS AND
RESULTS: Medicare claims and enrollment data were used to calculate age, sex, and race-adjusted rates of CAS and CEA for Medicare beneficiaries in each of 306 hospital referral regions between 1998 and 2007. Procedures were identified using a combination of Current Procedural Terminology codes as well as diagnostic and procedural ICD-9 codes. Overall, the rate of carotid revascularization has fallen slightly over the last decade (3.8 procedures per 1000 in 1998, 3.1 procedures per 1000 in 2007; P<0.0001). Although the use of CEA decreased, from 3.6 to 2.5 procedures per 1000 beneficiaries in 2007 (P<0.0001), the use of CAS has increased >4-fold between 1998 and 2007, growing from 0.1 to 0.6 CAS procedures per 1000 beneficiaries (P<0.0001). Further, CAS rapidly disseminated across the country over the last decade. In 1998, 66% of hospital referral regions had a hospital that performed CAS; however, by 2007, nearly all (95%) hospital referral regions performed CAS (P<0.0001). Last, in regions with the highest utilization rates of CAS, it appeared that CAS was performed as a substitute for CEA. There was little evidence that CAS was being performed in addition to CEA, as no correlation existed between regional rates of CAS and CEA (r=0.06).
CONCLUSIONS: Even though CEA was used less frequently in 2007 than 1998, the use of CAS has grown significantly. Although regional variation in the use of CEA has remained fairly constant, regional variation has increased in the use of CAS. Given these changes in practice patterns, careful examination of the efficacy and cost-effectiveness of CAS is necessary.