title: Validation of the supplemented Spetzler-Martin grading system for brain arteriovenous malformations in a multicenter cohort of 1009 surgical patients.
abstract: BACKGROUND
  The supplementary grading system for brain arteriovenous malformations (AVMs) was introduced in 2010 as a tool for improving preoperative risk prediction and selecting surgical patients.
  
  
  OBJECTIVE
  To demonstrate in this multicenter validation study that supplemented Spetzler-Martin (SM-Supp) grades have greater predictive accuracy than Spetzler-Martin (SM) grades alone.
  
  
  METHODS
  Data collected from 1009 AVM patients who underwent AVM resection were used to compare the predictive powers of SM and SM-Supp grades. Patients included the original 300 University of California, San Francisco patients plus those treated thereafter (n = 117) and an additional 592 patients from 3 other centers.
  
  
  RESULTS
  In the combined cohort, the SM-Supp system performed better than SM system alone: area under the receiver-operating characteristics curve (AUROC) = 0.75 (95% confidence interval, 0.71-0.78) for SM-Supp and AUROC = 0.69 (95% confidence interval, 0.65-0.73) for SM (P < .001). Stratified analysis fitting models within 3 different follow-up groupings (<6 months, 6 months-2 years, and >2 years) demonstrated that the SM-Supp system performed better than SM system for both medium (AUROC = 0.71 vs 0.62; P = .003) and long (AUROC = 0.69 vs 0.58; P = .001) follow-up. Patients with SM-Supp grades ≤6 had acceptably low surgical risks (0%-24%), with a significant increase in risk for grades >6 (39%-63%).
  
  
  CONCLUSIONS
  This study validates the predictive accuracy of the SM-Supp system in a multicenter cohort. An SM-Supp grade of 6 is a cutoff or boundary for AVM operability. Supplemented grading is currently the best method of estimating neurological outcomes after AVM surgery, and we recommend it as a starting point in the evaluation of AVM operability.
authors.affiliation: *Department of Anesthesia and Perioperative Care, ‡Department of Epidemiology and Biostatistics, §Center for Cerebrovascular Research, and ¶Department of Neurological Surgery, University of California, San Francisco, California; ‖Department of Neurological Surgery, Macquarie University, Sydney, Australia; #Department of Neurological Surgery, Massachusetts General Hospital, Boston, Massachusetts; **Division of Neurological Surgery, Barrow Neurological Institute, Phoenix, Arizona.
authors.forename: Helen
authors.initials: H
authors.lastname: Kim
authors.forename: Adib A
authors.initials: AA
authors.lastname: Abla
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Nelson
authors.forename: Charles E
authors.initials: CE
authors.lastname: McCulloch
authors.forename: David
authors.initials: D
authors.lastname: Bervini
authors.forename: Michael K
authors.initials: MK
authors.lastname: Morgan
authors.forename: Christopher
authors.initials: C
authors.lastname: Stapleton
authors.forename: Brian P
authors.initials: BP
authors.lastname: Walcott
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Ogilvy
authors.forename: Robert F
authors.initials: RF
authors.lastname: Spetzler
authors.forename: Michael T
authors.initials: MT
authors.lastname: Lawton
mesh_terms: D000328:Adult; D000367:Age Factors; D019540:Area Under Curve; D001164:Arteriovenous Fistula / Q000175:diagnosis / Q000601:surgery*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000175:diagnosis / Q000601:surgery*; D008297:Male; D008866:Microsurgery; D018579:Patient Selection; D011237:Predictive Value of Tests; D012372:ROC Curve; D018570:Risk Assessment; D012720:Severity of Illness Index; D016896:Treatment Outcome; D055815:Young Adult