title: Generalizability of Dutch Prediction Models for Low Hemoglobin Deferral: A Study on External Validation and Updating in Swiss Whole Blood Donors.
abstract: BACKGROUND
  Sex-specific prediction models for low hemoglobin (Hb) deferral have been developed in Dutch whole blood donors. In this study, we validated and updated the models in a cohort of Swiss whole blood donors.
  
  
  METHODS
  Prospectively collected data from 53,772 Swiss whole blood donors were used. The predictive performance of the Dutch models was assessed in terms of calibration (agreement between predicted probabilities and observed frequencies) and discrimination (ability to discriminate between deferred and approved donors). The models were updated by revising the strength of the individual predictors in the models.
  
  
  RESULTS
  A total of 1,065 men (3.3%) and 2,063 women (9.7%) were deferred from donation because of a low Hb level. Validation in Swiss donors demonstrated underestimation of predicted risks and significantly lower discriminative ability. The predictive effects of most predictors were weaker in Swiss donors. Updating the models increased the calibration for both men and women, and slightly increased the discriminative ability in men.
  
  
  CONCLUSIONS
  Validation of the Dutch prediction models in Swiss whole blood donors showed lower, though adequate performance. In general, the Dutch prediction models can reliably predict the risk of Hb deferral, although for application in other countries small adaptations are necessary.
authors.affiliation: Sanquin Research, Department of Donor Studies, Amsterdam, The Netherlands.
authors.forename: A Mireille
authors.initials: AM
authors.lastname: Baart
authors.affiliation: Interregional Blood Transfusion Service SRC Ltd, Berne, Switzerland.
authors.forename: Stefano
authors.initials: S
authors.lastname: Fontana
authors.affiliation: Interregional Blood Transfusion Service SRC Ltd, Berne, Switzerland.
authors.forename: Anita
authors.initials: A
authors.lastname: Tschaggelar
authors.affiliation: EMGO Institute for Health and Care Research, Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Martijn W
authors.initials: MW
authors.lastname: Heymans
authors.affiliation: Sanquin Research, Department of Donor Studies, Amsterdam, The Netherlands.
authors.forename: Wim L A M
authors.initials: WL
authors.lastname: de Kort
keywords: Blood donors; Donor deferral; External validation; Hemoglobin; Prediction model