title: External validation of a clinical scoring system for the risk of gestational diabetes mellitus.
abstract: OBJECTIVE
  A prediction rule for gestational diabetes mellitus (GDM) could be helpful in early detection and increased efficiency of screening. A prediction rule by means of a clinical scoring system is available, but has never been validated externally. The aim of this study was to validate the scoring system.
  
  
  METHODS
  We used data from a prospective cohort study. Women were assigned a score based on age, BMI and ethnicity. Performance of the scoring system was evaluated in terms of discrimination and calibration (agreement between clinical score and observed probability of GDM). We compared the efficiency of a screening strategy derived from the scoring system with conventional screening.
  
  
  RESULTS
  We studied 1266 women. Forty-seven women had GDM (3.7%). The scoring system discriminated moderately (area under the curve=0.64 (95% CI 0.56-0.72)). Calibration was limited (chi(2)=8.89, p=0.06). The screening strategy derived from the scoring system reduced the number of women needed to be screened with 25% for a comparable detection rate to universal screening.
  
  
  CONCLUSIONS
  Despite moderate discriminative capacity and calibration of the scoring system, the screening strategy based on the scoring system appears clinically useful. There is need for better prediction models for GDM.
authors.affiliation: Department of Obstetrics and Gynaecology, Academic Medical Centre, Amsterdam, The Netherlands. Marsha.vanLeeuwen@amc.uva.nl
authors.forename: M
authors.initials: M
authors.lastname: van Leeuwen
authors.forename: B C
authors.initials: BC
authors.lastname: Opmeer
authors.forename: E J K
authors.initials: EJ
authors.lastname: Zweers
authors.forename: E
authors.initials: E
authors.lastname: van Ballegooie
authors.forename: H G
authors.initials: HG
authors.lastname: ter Brugge
authors.forename: H W
authors.initials: HW
authors.lastname: de Valk
authors.forename: G H A
authors.initials: GH
authors.lastname: Visser
authors.forename: B W J
authors.initials: BW
authors.lastname: Mol
mesh_terms: D000328:Adult; D019540:Area Under Curve; D015992:Body Mass Index; D015331:Cohort Studies; D016640:Diabetes, Gestational / Q000453:epidemiology*; D005260:Female; D006801:Humans; D009426:Netherlands / Q000453:epidemiology; D011237:Predictive Value of Tests; D011247:Pregnancy; D011446:Prospective Studies; D044469:Racial Groups; D015203:Reproducibility of Results; D012307:Risk Factors