title: Predicting asthma in preschool children with asthma-like symptoms: validating and updating the PIAMA risk score.
abstract: BACKGROUND
  The Prevention and Incidence of Asthma and Mite Allergy (PIAMA) risk score predicts the probability of having asthma at school age among preschool children with suggestive symptoms.
  
  
  OBJECTIVE
  We sought to externally validate the PIAMA risk score at different ages and in ethnic and socioeconomic subgroups of children in addition to updating it.
  
  
  METHODS
  We studied 2877 children with preschool asthma-like symptoms participating in the multiethnic, prospective, population-based cohort study Generation R. The PIAMA risk score was assessed at preschool age, and asthma was predicted at age 6 years. Discrimination (concordance index [C-index]) and calibration were calculated. The PIAMA risk score was updated, and its performance was similarly analyzed.
  
  
  RESULTS
  At age 6 years, 6% (168/2877) of the children had asthma. The discriminative ability of the original PIAMA risk score to predict asthma in Generation R was similar compared with that in the PIAMA cohort (C-index = 0.74 vs 0.71). The predicted risks by using the original PIAMA risk score for having asthma at the age of 6 years tended to be slightly higher than the observed risks (8% vs 6%). No differences in discriminative ability were found at different ages or in ethnic and socioeconomic subgroups (P > .05). The updated PIAMA risk score had a C-index of 0.75.
  
  
  CONCLUSIONS
  The PIAMA risk score showed good external validity. The discriminative ability was similar at different ages and in ethnic and socioeconomic subgroups of preschool children, which suggests good generalizability. Further studies are needed to reproduce the predictive performance of the updated PIAMA risk score in other populations and settings and to assess its clinical relevance.
authors.affiliation: Generation R Study Group, Erasmus Medical Center, Rotterdam, The Netherlands; Department of Public Health, Erasmus Medical Center, Rotterdam, The Netherlands. Electronic address: e.hafkamp@erasmusmc.nl.
authors.forename: Esther
authors.initials: E
authors.lastname: Hafkamp-de Groen
authors.forename: Hester F
authors.initials: HF
authors.lastname: Lingsma
authors.forename: Daan
authors.initials: D
authors.lastname: Caudri
authors.forename: Deborah
authors.initials: D
authors.lastname: Levie
authors.forename: Alet
authors.initials: A
authors.lastname: Wijga
authors.forename: Gerard H
authors.initials: GH
authors.lastname: Koppelman
authors.forename: Liesbeth
authors.initials: L
authors.lastname: Duijts
authors.forename: Vincent W V
authors.initials: VW
authors.lastname: Jaddoe
authors.forename: Henriëtte A
authors.initials: HA
authors.lastname: Smit
authors.forename: Marjan
authors.initials: M
authors.lastname: Kerkhof
authors.forename: Henriëtte A
authors.initials: HA
authors.lastname: Moll
authors.forename: Albert
authors.initials: A
authors.lastname: Hofman
authors.forename: Ewout W
authors.initials: EW
authors.lastname: Steyerberg
authors.forename: Johan C
authors.initials: JC
authors.lastname: de Jongste
authors.forename: Hein
authors.initials: H
authors.lastname: Raat
mesh_terms: D001249:Asthma / Q000175:diagnosis* / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D005006:Ethnicity; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D008297:Male; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D012307:Risk Factors; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires
keywords: Asthma; C-index; Concordance index; LR+; LR−; Likelihood ratio of a negative test result; Likelihood ratio of a positive test result; NPV; Negative predictive value; OR; Odds ratio; PIAMA; PPV; Positive predictive value; Prevention and Incidence of Asthma and Mite Allergy; Prevention and Incidence of Asthma and Mite Allergy risk score; birth cohort; children; external validation; prediction; prognosis; updating; wheeze