title: Prediction of 60-Day Case Fatality After Aneurysmal Subarachnoid Hemorrhage: External Validation of a Prediction Model.
abstract: External validation of prognostic models is crucial but rarely done. Our aim was to externally validate a prognostic model to predict 60-day case fatality after aneurysmal subarachnoid hemorrhage developed from the International Subarachnoid Aneurysm Trial in a retrospective unselected cohort of subarachnoid hemorrhage patients.
  
  
  
  The model's predictors were age, aneurysm size, Fisher grade, and World Federation of Neurological Surgeons grade. Two versions of the model were validated: one with World Federation of Neurological Surgeons grade scored at admission and the other with World Federation of Neurological Surgeons grade at treatment decision. The outcome was 60-day case fatality. Performance of the model was assessed by studying discrimination, expressed by the area under the receiver operating characteristic curve, and calibration.
  
  
  
  University hospital.
  
  
  
  We analyzed data from 307 consecutive aneurysmal subarachnoid hemorrhage patients admitted between 2007 and 2011 (validation cohort).
  
  
  
  None.
  
  
  
  The observed 60-day case fatality rate was 30.6%. Discrimination was good, and differed between the model with World Federation of Neurological Surgeons grade at treatment decision (area under the receiver operating characteristic curve, 0.89) and at admission (area under the receiver operating characteristic curve, 0.82). Mean predicted probabilities were lower than observed: 17.0% (model with World Federation of Neurological Surgeons grade at admission) and 17.7% (model with World Federation of Neurological Surgeons grade at treatment decision).
  
  
  
  The model discriminated well between patients who died or survived within 60 days. In addition, we found that using World Federation of Neurological Surgeons grade at moment of treatment decision of the ruptured aneurysm improved model performance. However, since predicted probabilities were much lower than observed probabilities, the International Subarachnoid Aneurysm Trial prediction model needs to be adapted to be used in clinical practice.
authors.affiliation: 1Department of Intensive Care, University Medical Center Rotterdam, Rotterdam, The Netherlands. 2Department of Neurology, University Medical Center Rotterdam, Rotterdam, The Netherlands. 3Department of Radiology, University Medical Center Rotterdam, Rotterdam, The Netherlands. 4Department of Public Health, University Medical Center Rotterdam, Rotterdam, The Netherlands. 5Erasmus MC Stroke Center, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands. 6Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Simone A
authors.initials: SA
authors.lastname: Dijkland
authors.forename: Bob
authors.initials: B
authors.lastname: Roozenbeek
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Brouwer
authors.forename: Hester F
authors.initials: HF
authors.lastname: Lingsma
authors.forename: Diederik W
authors.initials: DW
authors.lastname: Dippel
authors.forename: Leonie J
authors.initials: LJ
authors.lastname: Vergouw
authors.forename: Mervyn D
authors.initials: MD
authors.lastname: Vergouwen
authors.forename: Mathieu
authors.initials: M
authors.lastname: van der Jagt
mesh_terms: D000328:Adult; D000367:Age Factors; D005260:Female; D006785:Hospitals, University; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012372:ROC Curve; D015203:Reproducibility of Results; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D013345:Subarachnoid Hemorrhage / Q000401:mortality*