Analysis of Medicare Payments for Preoperative Imaging Before Carotid Endarterectomy

Abstract

Evaluation of carotid disease may be performed by multiple radiographic modalities. Current guidelines do not have strong recommendation regarding the use of cross-sectional imaging (CSI), computed tomography (CT) or magnetic resonance imaging (MRI) of the neck, before surgical intervention. We sought to describe the use of and Medicare payments in preoperative carotid imaging and associated outcomes for patients undergoing carotid endarterectomy (CEA) for asymptomatic disease. We used a 20% Medicare sample from 2006 to 2014 identifying patients undergoing CEA. We evaluated preoperative carotid ultrasound and CSI use before CEA. We calculated average payments of each study from the carrier file and revenue center file. Imaging payments included both the professional component and the technical component. Claims with a reimbursement of $0 and studies in which payment for both the technical component and professional component could not be identified were excluded from the overall calculation to determine average payment per study. Inpatient reimbursements according to diagnosis-related groups 37 to 39 were calculated according to CSI use. After stratifying by CSI use, we compared hospital length of stay (LOS), postoperative stroke, and carotid re-exploration rates using multivariable regression. A total of 58,993 CEAs were identified with preoperative carotid imaging. The average age was 74.8 ± 7.5 years, and 56.0% were men. Of these, 19,678 (33%) patients has ultrasound alone with an average of (2.4 ± 1.9) examinations before CEA. The CSI cohort had 39,315 patients with an average of 0.95 ± 0.86 neck CT scans and 0.47 ± 0.7 MRI scans in addition to 2.5 ± 2.1 ultrasound scans. The average payment was $140 ± $40 for ultrasound, $282 ± $94 for CT, and $410 ± $146 for MRI (Table I). The average inpatient reimbursements were $6088 ± $4125 for patients without CSI compared with $6784 ± $3989 for patients with CSI (P < .001; Table II). The average LOS during CEA admission was 2.5 ± 3.7 days. Higher age and female sex were associated with longer LOS; however, preoperative CSI was not associated with shorter LOS. The overall postoperative stroke rate was 0.5%, and carotid re-exploration rate was 0.5%; CSI was not associated with lower rates of postoperative stroke or re-exploration. Our analysis found preoperative imaging to include CSI in nearly two-thirds of patients before CEA for asymptomatic disease. CSI was not associated with improved patient outcomes regarding shorter LOS, lower postoperative stroke, and lower rates of reoperation. As imaging and inpatient payments were higher in patients with CSI, further work is needed to understand when CSI is appropriate before surgical intervention to appropriately allocate health care resources.Table IPayments for pre-operative imaging, expressed in U.S. dollarsCarotid ultrasoundCT neckMRI neckTotal (mean ± SD)140 ± 40282 ± 94410 ± 146Median (IQR)136 (116-154)276 (236-320)380 (311-470)Professional Component (mean ± SD)26 ± 656 ± 1755 ± 18Median (IQR)24 (23-25)63 (46-60)51 (46-71)Technical Component (mean ± SD)114 ± 35213 ± 75353 ± 156Median (IQR)117 (107-129)234 (179-256)348 (265-428) Open table in a new tab Table IIAverage pre-operative imaging studies with associated payments and inpatient reimbursementsMedicare paymentsNo CSI (n = 19,678)With CSI (n = 39,315)P-valueAverage number of Carotid DUS2.4 ± 1.92.5 ± 2.1<.001Average number of CT neck00.95 ± 0.86n/aAverage number of MRI neck00.47 ± 0.7n/aTotal Pre-operative imaging payments$336 ± 54$872 ± 120<.001Average inpatient reimbursements$6088 ± 4125$6784 ± 3989<.001Pre-operative imaging + inpatient payments$6424 ± 4133$7656 ± 4050<.001 Open table in a new tab