title: Validation of a prognostic score for early mortality in severe head injury cases.
abstract: OBJECTIVE
  Traumatic brain injury (TBI) represents a large health and economic burden. Because of the inability of previous randomized controlled trials (RCTs) on TBI to demonstrate the expected benefit of reducing unfavorable outcomes, the IMPACT (International Mission on Prognosis and Analysis of Clinical Trials in TBI) and CRASH (Corticosteroid Randomisation After Significant Head Injury) studies provided new methods for performing prognostic studies of TBI. This study aimed to develop and externally validate a prognostic model for early death (within 48 hours). The secondary aim was to identify patients who were more likely to succumb to an early death to limit their inclusion in RCTs and to improve the efficiency of RCTs.
  
  
  METHODS
  The derivation cohort was recruited at 1 center, Hospital 12 de Octubre, Madrid (1990-2003, 925 patients). The validation cohort was recruited in 2004-2006 from 7 study centers (374 patients). The eligible patients had suffered closed severe TBIs. The study outcome was early death (within 48 hours post-TBI). The predictors were selected using logistic regression modeling with bootstrapping techniques, and a penalized reduction was used. A risk score was developed based on the regression coefficients of the variables included in the final model.
  
  
  RESULTS
  In the validation set, the final model showed a predictive ability of 50% (Nagelkerke R(2)), with an area under the receiver operating characteristic curve of 89% and an acceptable calibration (goodness-of-fit test, p = 0.32). The final model included 7 variables, and it was used to develop a risk score with a range from 0 to 20 points. Age provided 0, 1, 2, or 3 points depending on the age group; motor score provided 0 points, 2 (untestable), or 3 (no response); pupillary reactivity, 0, 2 (1 pupil reacted), or 6 (no pupil reacted); shock, 0 (no) or 2 (yes); subarachnoid hemorrhage, 0 or 1 (severe deposit); cisternal status, 0 or 3 (compressed/absent); and epidural hematoma, 0 (yes) or 2 (no). Based on the risk of early death estimated with the model, 4 risk of early death groups were established: low risk, sum score 0-3 (< 1% predicted mortality); moderate risk, sum score 4-8 (predicted mortality between 1% and 10%); high risk, sum score 9-12 (probability of early death between 10% and 50%); and very high risk, sum score 13-20 (early mortality probability > 50%). This score could be used for selecting patients for clinical studies. For example, if patients with very high risk scores were excluded from our study sample, the patients included (eligibility score < 13) would represent 80% of the original sample and only 23% of the patients who died early.
  
  
  CONCLUSIONS
  The combination of Glasgow Coma Scale score, CT scanning results, and secondary insult data into a prognostic score improved the prediction of early death and the classification of TBI patients.
authors.affiliation: Department of Neurosurgery and.
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Gómez
authors.forename: Javier
authors.initials: J
authors.lastname: de-la-Cruz
authors.forename: David
authors.initials: D
authors.lastname: Lora
authors.forename: Luis
authors.initials: L
authors.lastname: Jiménez-Roldán
authors.forename: Gregorio
authors.initials: G
authors.lastname: Rodríguez-Boto
authors.forename: Rosario
authors.initials: R
authors.lastname: Sarabia
authors.forename: Juan
authors.initials: J
authors.lastname: Sahuquillo
authors.forename: Roberto
authors.initials: R
authors.lastname: Lastra
authors.forename: Jesus
authors.initials: J
authors.lastname: Morera
authors.forename: Eglis
authors.initials: E
authors.lastname: Lazo
authors.forename: Jaime
authors.initials: J
authors.lastname: Dominguez
authors.forename: Javier
authors.initials: J
authors.lastname: Ibañez
authors.forename: Marta
authors.initials: M
authors.lastname: Brell
authors.forename: Adolfo
authors.initials: A
authors.lastname: de-la-Lama
authors.forename: Ramiro D
authors.initials: RD
authors.lastname: Lobato
authors.forename: Alfonso
authors.initials: A
authors.lastname: Lagares
mesh_terms: D000328:Adult; D001930:Brain Injuries / Q000000981:diagnostic imaging* / Q000401:mortality* / Q000628:therapy; D016208:Databases, Factual / Q000592:standards; D005260:Female; D015600:Glasgow Coma Scale / Q000592:standards*; D006801:Humans; D015601:Injury Severity Score; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: GCS = Glasgow Coma Scale; RCT = randomized controlled trial; ROC = receiver operating characteristic; SAH = subarachnoid hemorrhage; TBI = traumatic brain injury; early death; external validation; prognosis; severe traumatic brain injury