title: Systematic review of prognostic models in traumatic brain injury.
abstract: BACKGROUND
  Traumatic brain injury (TBI) is a leading cause of death and disability world-wide. The ability to accurately predict patient outcome after TBI has an important role in clinical practice and research. Prognostic models are statistical models that combine two or more items of patient data to predict clinical outcome. They may improve predictions in TBI patients. Multiple prognostic models for TBI have accumulated for decades but none of them is widely used in clinical practice. The objective of this systematic review is to critically assess existing prognostic models for TBI METHODS: Studies that combine at least two variables to predict any outcome in patients with TBI were searched in PUBMED and EMBASE. Two reviewers independently examined titles, abstracts and assessed whether each met the pre-defined inclusion criteria.
  
  
  RESULTS
  A total of 53 reports including 102 models were identified. Almost half (47%) were derived from adult patients. Three quarters of the models included less than 500 patients. Most of the models (93%) were from high income countries populations. Logistic regression was the most common analytical strategy to derived models (47%). In relation to the quality of the derivation models (n:66), only 15% reported less than 10% pf loss to follow-up, 68% did not justify the rationale to include the predictors, 11% conducted an external validation and only 19% of the logistic models presented the results in a clinically user-friendly way
  
  
  CONCLUSIONS
  Prognostic models are frequently published but they are developed from small samples of patients, their methodological quality is poor and they are rarely validated on external populations. Furthermore, they are not clinically practical as they are not presented to physicians in a user-friendly way. Finally because only a few are developed using populations from low and middle income countries, where most of trauma occurs, the generalizability to these setting is limited.
authors.affiliation: Nutrition and Public Health Intervention Research Unit, Epidemiology and Population Health Department, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK. pablo.perel@lshtm.ac.uk
authors.forename: Pablo
authors.initials: P
authors.lastname: Perel
authors.forename: Phil
authors.initials: P
authors.lastname: Edwards
authors.forename: Reinhard
authors.initials: R
authors.lastname: Wentz
authors.forename: Ian
authors.initials: I
authors.lastname: Roberts
mesh_terms: D001930:Brain Injuries / Q000150:complications / Q000175:diagnosis* / Q000401:mortality; D023261:Glasgow Outcome Scale; D006801:Humans; D015233:Models, Statistical; D011379:Prognosis; D015203:Reproducibility of Results; D016896:Treatment Outcome