title: External validation of prognostic models to predict risk of gestational diabetes mellitus in one Dutch cohort: prospective multicentre cohort study.
abstract: OBJECTIVE
  To perform an external validation and direct comparison of published prognostic models for early prediction of the risk of gestational diabetes mellitus, including predictors applicable in the first trimester of pregnancy.
  
  
  METHODS
  External validation of all published prognostic models in large scale, prospective, multicentre cohort study.
  
  
  METHODS
  31 independent midwifery practices and six hospitals in the Netherlands.
  
  
  METHODS
  Women recruited in their first trimester (<14 weeks) of pregnancy between December 2012 and January 2014, at their initial prenatal visit. Women with pre-existing diabetes mellitus of any type were excluded.
  
  
  METHODS
  Discrimination of the prognostic models was assessed by the C statistic, and calibration assessed by calibration plots.
  
  
  RESULTS
  3723 women were included for analysis, of whom 181 (4.9%) developed gestational diabetes mellitus in pregnancy. 12 prognostic models for the disorder could be validated in the cohort. C statistics ranged from 0.67 to 0.78. Calibration plots showed that eight of the 12 models were well calibrated. The four models with the highest C statistics included almost all of the following predictors: maternal age, maternal body mass index, history of gestational diabetes mellitus, ethnicity, and family history of diabetes. Prognostic models had a similar performance in a subgroup of nulliparous women only. Decision curve analysis showed that the use of these four models always had a positive net benefit.
  
  
  CONCLUSIONS
  In this external validation study, most of the published prognostic models for gestational diabetes mellitus show acceptable discrimination and calibration. The four models with the highest discriminative abilities in this study cohort, which also perform well in a subgroup of nulliparous women, are easy models to apply in clinical practice and therefore deserve further evaluation regarding their clinical impact.
authors: Department of Obstetrics, Division Woman and Baby, University Medical Centre Utrecht, KE.04.123.1, PO box 85090, 3508 AB, Utrecht, Netherlands m.deruiter-7@umcutrecht.nl.
authors: Marije
authors: M
authors: Lamain-de Ruiter
authors: Department of Obstetrics, Division Woman and Baby, University Medical Centre Utrecht, KE.04.123.1, PO box 85090, 3508 AB, Utrecht, Netherlands.
authors: Anneke
authors: A
authors: Kwee
authors: Julius Centre for Health Sciences and Primary Care, University Medical Centre Utrecht, Utrecht, Netherlands.
authors: Christiana A
authors: CA
authors: Naaktgeboren
authors: Livive, Centre for Obstetrics, Tilburg, Netherlands.
authors: Inge
authors: I
authors: de Groot
authors: Department of Obstetrics, Meander Medical Centre, Amersfoort, Netherlands.
authors: Inge M
authors: IM
authors: Evers
authors: Department of Neonatology, Division Woman and Baby, University Medical Centre Utrecht, Utrecht, Netherlands.
authors: Floris
authors: F
authors: Groenendaal
authors: Department of Obstetrics, Zuwe Hofpoort Hospital, Woerden, Netherlands.
authors: Yolanda R
authors: YR
authors: Hering
authors: Department of Obstetrics, Gelre Hospital, Apeldoorn, Netherlands.
authors: Anjoke J M
authors: AJ
authors: Huisjes
authors: Department of Obstetrics, Hospital Rivierenland, Tiel, Netherlands.
authors: Cornel
authors: C
authors: Kirpestein
authors: Department of Obstetrics, St Antonius Hospital, Nieuwegein, Netherlands.
authors: Wilma M
authors: WM
authors: Monincx
authors: Centre for Infectious Diseases Research, Diagnostics and Screening (IDS), National Institute for Public Health and the Environment (RIVM), Bilthoven, Netherlands.
authors: Jacqueline E
authors: JE
authors: Siljee
authors: Midwifery practice Verloskundigen Amersfoort, Amersfoort, Netherlands.
authors: Annewil
authors: A
authors: Van 't Zelfde
authors: Department of Obstetrics, St Elisabeth Hospital, Tilburg, Netherlands.
authors: Charlotte M
authors: CM
authors: van Oirschot
authors: Midwifery practice GCM, Maarssenbroek, Netherlands.
authors: Simone A
authors: SA
authors: Vankan-Buitelaar
authors: Midwifery practice Het Wonder, Houten, Netherlands.
authors: Mariska A A W
authors: MA
authors: Vonk
authors: Netherlands Institute for health services research (NIVEL), Utrecht, Netherlands.
authors: Therese A
authors: TA
authors: Wiegers
authors: Department of Obstetrics, Deventer Hospital, Deventer, Netherlands.
authors: Joost J
authors: JJ
authors: Zwart
authors: Department of Obstetrics, Division Woman and Baby, University Medical Centre Utrecht, KE.04.123.1, PO box 85090, 3508 AB, Utrecht, Netherlands.
authors: Arie
authors: A
authors: Franx
authors: Julius Centre for Health Sciences and Primary Care, University Medical Centre Utrecht, Utrecht, Netherlands.
authors: Karel G M
authors: KG
authors: Moons
authors: Department of Obstetrics, Division Woman and Baby, University Medical Centre Utrecht, KE.04.123.1, PO box 85090, 3508 AB, Utrecht, Netherlands Department of Obstetrics and Gynaecology, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, Netherlands.
authors: Maria P H
authors: MP
authors: Koster
mesh_terms: D000328:Adult; D015992:Body Mass Index; D002138:Calibration; D003920:Diabetes Mellitus / Q000235:genetics; D016640:Diabetes, Gestational / Q000453:epidemiology* / Q000208:ethnology; D005260:Female; D006801:Humans; D008423:Maternal Age; D009426:Netherlands / Q000453:epidemiology; D010298:Parity; D011237:Predictive Value of Tests; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011446:Prospective Studies; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D013223:Statistics as Topic