title: A New Risk Index for Predicting Outcomes among Patients Undergoing Carotid Endarterectomy in Large Administrative Data Sets.
abstract: BACKGROUND
  We developed and validated a new index to provide risk adjustment and to predict in-hospital patient mortality and other outcomes in patients undergoing carotid endarterectomy (CEA).
  
  
  METHODS
  The primary endpoint was occurrence of stroke, cardiac complications, or death during hospitalization for CEA derived from the Nationwide Inpatient Sample. Multivariate logistic regression was performed to identify the effect of clinical and demographic factors on occurrence of the primary endpoint. Data from 2005 to 2006 (study period 1) were used to derive risk index score whereas data from 2007 to 2009 (study period 2) were used for validation of the risk index.
  
  
  RESULTS
  A total of 120,633 patients with mean age in years [ ±SD] of 71.1[ ±9.5] (42.4% women) underwent CEA during the derivation period. The rate of occurrence of composite endpoint during study period 1 was 3.1%. Predictors of the composite endpoint were (odds ratio [OR], P value) as follows: age 70 years or older (1.15, .013 assigned 1 point), atrial fibrillation (3.18, <.0001 assigned 3 points), Congestive Heart Failure (CHF) (1.81, <.0001 assigned 2 points), cigarette smoking (1.64, <.0001 assigned 2 points), symptomatic status (1.87, <.001 assigned 2 points), and chronic renal failure (1.64, <.0001 assigned 2 points). When applied to the validation cohort (n = 71,222), patients with scores 0-1 (OR 1.6, 95% confidence interval [CI] 1.5-1.8), scores 2-3 (OR 4.0, 95% CI 3.8-4.3), scores 4-5 (OR 7.5, 95% CI 6.8-8.2), and scores greater than 5 (OR 10.9, 95% CI 9.8-12.2) had composite rates of endpoint. The receiver operating characteristic curve of the risk index was 68.5% [±SE 0.5%].
  
  
  CONCLUSIONS
  New risk index will assist in risk adjustment for analyses of outcomes in large administrative data sets for comparative studies involving patients undergoing CEA.
authors.affiliation: Zeenat Qureshi Stroke Institute, St. Cloud, Minnesota; Department of Neurology and Ophthalmology, Michigan State University, East Lansing, Michigan. Electronic address: chaudhrys208@gmail.com.
authors.forename: Saqib A
authors.initials: SA
authors.lastname: Chaudhry
authors.affiliation: Zeenat Qureshi Stroke Institute, St. Cloud, Minnesota.
authors.forename: Mohammad R
authors.initials: MR
authors.lastname: Afzal
authors.affiliation: Department of Neurology and Ophthalmology, Michigan State University, East Lansing, Michigan.
authors.forename: Abdulkader
authors.initials: A
authors.lastname: Kassab
authors.affiliation: Department of Neurology and Ophthalmology, Michigan State University, East Lansing, Michigan.
authors.forename: Syed I
authors.initials: SI
authors.lastname: Hussain
authors.affiliation: Zeenat Qureshi Stroke Institute, St. Cloud, Minnesota.
authors.forename: Adnan I
authors.initials: AI
authors.lastname: Qureshi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016208:Databases, Factual / Q000706:statistics & numerical data; D016894:Endarterectomy, Carotid / Q000009:adverse effects*; D005260:Female; D006331:Heart Diseases / Q000601:surgery; D017052:Hospital Mortality; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000175:diagnosis*; D011237:Predictive Value of Tests; D012372:ROC Curve; D015203:Reproducibility of Results; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D014481:United States / Q000453:epidemiology
keywords: Risk index; carotid endarterectomy; national database; outcome prediction; validation study