Regional Variation in Carotid Artery Stenting and Endarterectomy in the Medicare Population

Abstract

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.

Surgeon Case Volume and 30-Day Mortality After Carotid Endarterectomy Among Contemporary Medicare Beneficiaries

“…This is consistent with recent studies among Medicare beneficiaries, 11,23,24 which found a reduction in the overall rate of carotid revascularizations over 2001 to 2007. This may be explained by improved medical management of atherosclerosis in general or carotid stenosis, leading to a reduction in the incidence of asymptomatic or symptomatic carotid stenosis, [25][26][27] a perception of reduced relative benefit from carotid revascularization especially in asymptomatic patients, [28][29][30][31] improved or increased use of diagnostic procedures allowing for better patient selection, 24 or dissemination of evidence on the increased periprocedural risks in certain subpopulations.…”

“…10 Over the following years, the number of CAS procedures performed among Medicare beneficiaries grew, whereas the rate of CEA procedures declined. 11,12 We hypothesized that the reduction in the overall rate of CEAs in the Medicare beneficiaries may have caused case-volumes of the individual performing surgeons to decline, leading to worse periprocedural outcomes. The objective of this study is to examine the decline in past-year case-volumes of surgeons performing CEA before and after the NCD for CAS and to assess its effect on 30-day post-CEA mortality.…”

Early Outcomes After Carotid Artery Stenting Compared With Endarterectomy for Asymptomatic Carotid Stenosis

“…12 Regional variation in the use of CAS has also increased, and CAS seems to be displacing CEA in some parts of the United States. 13 Until additional evidence from large-scale randomized clinical trials becomes available, observational data may provide practical information to inform clinical practice, provided that confounding based on baseline differences in patients selected for these procedures can be minimized. Conventional multivariable analysis can adjust for measured confounders, propensity score matching attempts to reduce confounding by matching groups based on the estimated probability of receiving the treatment, and grouped-treatment analysis is a form of instrumental variable analysis that can potentially mitigate the effect of confounding by indication 14,15 by taking advantage of practice variation in the proportion of patients treated with CAS when compared with those treated with CEA at the hospital-level.…”

Consistency of Hemoglobin A1c Testing and Cardiovascular Outcomes in Medicare Patients With Diabetes

“…Stroke was defined using ICD‐9 codes, as published previously. We used a 1‐year look back to exclude patients in whom any of the cardiovascular events occurred in the past year 23, 24. We recorded the occurrence of a major lower‐extremity amputation at the patient level, using current procedural terminology codes indicative of above‐ or below‐knee amputation.…”