Analysis of Medicare Payments and Patient Outcomes With Pre-Operative Imaging for Carotid Endarterectomy

Abstract

The use of radiographic evaluation of carotid disease may vary, and current guidelines do not strongly recommend the use of cross-sectional imaging (CSI) prior to surgical intervention. We sought to describe the trends in preoperative carotid imaging and evaluate the associated clinical outcomes and Medicare payments for patients undergoing carotid endarterectomy (CEA) for asymptomatic carotid disease. We used a 20% Medicare sample from 2006 to 2014 identifying patients undergoing CEA for asymptomatic disease. We evaluated preoperative carotid ultrasound and CSI use: CT or MRI of the neck prior to CEA. We calculated average payments of each study from the carrier file and revenue center file. Imaging payments included both the professional component (PC) and the technical component (TC). Claims with a reimbursement of $0 and studies where payment for both the TC and PC could not be identified were excluded from the overall calculation to determine average payment per study. Inpatient reimbursements according to DRG 37-39 were calculated. We compared hospital length of stay (LOS), in hospital stroke, carotid re-exploration, and mortality according to CSI use. A total of 58,993 CEAs were identified with pre-operative carotid imaging. The average age was 74.8 ± 7.5 years, and 56.0% were men. A total of 19,678 (33%) patients had ultrasound alone with an average of (2.4 ± 1.9) exams prior to CEA. A total of 39,315 patients underwent CSI prior to CEA with 2.5 ± 2.1 ultrasounds, 0.95 ± 0.86 neck CTs and 0.47 ± 0.7 MRIs per patient. The average payment for ultrasound was $140 ± 40, $282 ± 94 for CT and $410 ± 146 for MRI. The average inpatient reimbursements were $7,413 ± 4,215 for patients without CSI compared with $7,792 ± 3,921 for patients with CSI, P < 0.001. The average LOS during CEA admission was 2.5 ± 3.7days. Patients with CSI had a slightly lower percentage of patients being discharged by postoperative day 2 compared with ultrasound alone (88.9% vs. 91.5%, respectively, P < 0.001). The overall in-hospital stroke rate was 0.38% and carotid re-exploration rate was 1.0% and there was no statistical significant difference between groups. Median follow-up was 3.9 years, and mortality at 8 years was 50% and did not statistically differ between groups. Our analysis found preoperative imaging to include CSI in nearly two-thirds of patients prior to CEA for asymptomatic disease. As imaging and inpatient payments were higher with patients with CSI further work is needed to understand when CSI is appropriate prior to surgical intervention to appropriately allocate healthcare resources.