Abstract 323: Utilization and Outcomes of Carotid Artery Stenting vs. Carotid Endarterectomy

Introduction: Carotid artery stenting is an alternative to carotid endarterectomy in average surgical-risk symptomatic patients and asymptomatic patients with ≥60% stenosis. We wanted to compare utilization and peri-procedural mortality between these procedures. Methods: The 2000-2013 National Inpatient Sample (NIS) was analyzed for admissions when procedures for carotid artery stenting (CAS) or carotid endarterectomy (CEA) were performed. Admissions when both procedures were performed were excluded. Trend of procedures and death during index admission was compared depending on prior cerebrovascular symptoms. Results: During the study period, 1991941 patients underwent CEA of which 9.12% were symptomatic and 343,741 patients underwent CAS of which 10.8% were symptomatic. Mean age for CAS vs CEA group was lower among both symptomatic (68.6 vs 69.6 yrs, p<0.001) and asymptomatic patients (70.7 vs 71.2 yrs, p<0.001). More males than females underwent CAS (57% vs 43%) and CEA (58% vs 42%). Both CAS and CEA during same admission was carried out in 20,875 (0.89%) patients. There was a rising trend of both CEA and CAS procedures in symptomatic and asymptomatic patients (ptrend < 0.001)(Figure A1 & B1). Trend of mortality has not changed significantly in all groups except for CEA in asymptomatic patients wherein mortality rate has decreased (ptrend <0.001)(Figure A2 & B2). On multivariable logistic regression analysis, associated conditions significant for mortality in symptomatic patients were atrial fibrillation (OR 2.05, p<0.001), myocardial infarction (OR 1.61, p=0.001) heart failure (OR 1.39, p=0.021) and malnutrition (OR 3.58, p<0.001). Adjusted likelihood of mortality after CAS vs CEA was higher in symptomatic (OR 3.78, p<0.001, C statistic 0.74) and asymptomatic patients (OR 2.00, p<0.001, C statistic 0.80). Conclusion: Utilization of CAS and CEA has increased over time. Mortality after CAS vs. CEA during index admission, remains high.

LIKELIHOOD INFERENCE IN AN AUTOREGRESSION WITH FIXED EFFECTS

We calculate the bias of the profile score for the regression coefficients in a multistratum autoregressive model with stratum-specific intercepts. The bias is free of incidental parameters. Centering the profile score delivers an unbiased estimating equation and, upon integration, an adjusted profile likelihood. A variety of other approaches to constructing modified profile likelihoods are shown to yield equivalent results. However, the global maximizer of the adjusted likelihood lies at infinity for any sample size, and the adjusted profile score has multiple zeros. Consistent parameter estimates are obtained as local maximizers inside or on an ellipsoid centered at the maximum likelihood estimator.

Volume-Based Referral for Cancer Surgery: Informing the Debate

PurposeMounting evidence suggests a relationship between hospital volume and outcomes after major cancer surgery; however, the absolute benefits of volume-based referral on a national basis are unclear.Patients and MethodsData from the Nationwide Inpatient Sample were used to measure the likelihood of operative mortality and a prolonged length of stay (LOS) after six cancer surgeries (prostatectomy, cystectomy, esophagectomy, pancreatectomy, pneumonectomy, and liver resection) between 1993 and 2003. Using sampling weights, the adjusted likelihood of the outcomes was used to calculate the number of lives saved (or prolonged LOS avoided) in the United States.ResultsThe magnitude of the volume–operative mortality effect varied from an adjusted odds ratio (OR) of 1.3 (95% CI, 0.8 to 2.3) for cystectomy to 4.9 (95% CI, 2.4 to 10.1) for pancreatectomy. After accounting for varying rates of procedure utilization, the lives saved per 100 surgeries regionalized ranged from 0.2 (95% CI, 0.12 to 0.24 lives saved) for prostatectomy to 9.2 (95% CI, 6.7 to 10.4 lives saved) for pancreatectomy. The volume–prolonged LOS effect varied from an adjusted OR of 0.9 (95% CI, 0.5 to 1.6) for liver resection to 4.8 (95% CI, 3.5 to 6.7) for prostatectomy. After accounting for procedure use, the number of prolonged hospitalizations avoided ranged from −1.7 (95% CI, −11.3 to 3.6 hospitalizations) to 14.3 (95% CI, 12.9 to 15.4 hospitalizations) per 100 surgeries regionalized for liver resection and prostatectomy, respectively.ConclusionFor patients undergoing major cancer surgery, the benefits of volume-based referral depend on the interplay between procedure utilization, the magnitude of effect, and the outcome chosen.