title: Updating methods improved the performance of a clinical prediction model in new patients.
abstract: OBJECTIVE
  Ideally, clinical prediction models are generalizable to other patient groups. Unfortunately, they perform regularly worse when validated in new patients and are then often redeveloped. While the original prediction model usually has been developed on a large data set, redevelopment then often occurs on the smaller validation set. Recently, methods to update existing prediction models with the data of new patients have been proposed. We used an existing model that preoperatively predicts the risk of severe postoperative pain (SPP) to compare five updating methods.
  
  
  METHODS
  The model was tested and updated with a set of 752 new patients (274 [36] with SPP). We studied the discrimination (ability to distinguish between patients with and without SPP) and calibration (agreement between the predicted risks and observed frequencies of SPP) of the five updated models in 283 other patients (100 [35%] with SPP).
  
  
  RESULTS
  Simple recalibration methods improved the calibration to a similar extent as revision methods that made more extensive adjustments to the original model. Discrimination could not be improved by any of the methods.
  
  
  CONCLUSIONS
  When the performance is poor in new patients, updating methods can be applied to adjust the model, rather than to develop a new model.
authors: Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands. k.j.m.janssen@umcutrecht.nl
authors: K J M
authors: KJ
authors: Janssen
authors: K G M
authors: KG
authors: Moons
authors: C J
authors: CJ
authors: Kalkman
authors: D E
authors: DE
authors: Grobbee
authors: Y
authors: Y
authors: Vergouwe
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement / Q000379:methods; D010149:Postoperative Pain / Q000175:diagnosis / Q000209:etiology*; D011379:Prognosis; D012307:Risk Factors; D012720:Severity of Illness Index