title: Cohort study to test the predictability of the NHS Institute for Innovation and Improvement Paediatric Early Warning System.
abstract: To test the predictability of the National Health Service Institute for Innovation and Improvement (NHSIII) Paediatric Early Warning System (PEWS) score to identify children at risk of developing critical illness.
  
  
  
  Cohort study.
  
  
  
  Admissions to all paediatric wards at the University Hospital of Wales between 1 December 2005 and 30 November 2006.
  
  
  
  Unscheduled paediatric high dependency unit (PHDU) admission, paediatric intensive care unit (PICU) admission and death.
  
  
  
  There were 9075 clinical observations from 1000 children. An NHSIII PEWS score of 2 or more, which triggers review, has a sensitivity of 73.2% (95% CI 62.2% to 82.4%), specificity of 75.2% (95% CI 74.3% to 76.1%), positive predictive value (PPV) of 2.6% (95% CI 2.0% to 3.4%), negative predictive value of 99.7% (95% CI 99.5% to 99.8%) and positive likelihood ratio of 3.0 (95% CI 2.6 to 3.4) for predicting PHDU admission, PICU admission or death. Six (37.5%) of the 16 children with an adverse outcome did not have an abnormal NHSIII PEWS score. The area under the receiver operating characteristic curve for the NHSIII PEWS score was 0.83 (95% CI 0.77 to 0.88).
  
  
  
  The NHSIII PEWS has a low PPV and its full implementation would result in a large number of false positive triggers. The issue with PEWS scores or triggers is neither their sensitivity nor children with high scores which require clinical interventions who are not 'false positives'; but their low specificity and low PPV arising from the large number of children with low but raised scores.
authors.affiliation: Public Health Wales, Cardiff, UK.
authors.forename: B W
authors.initials: BW
authors.lastname: Mason
authors.affiliation: Department of Paediatrics, Morriston Hospital, Swansea, UK.
authors.forename: E D
authors.initials: ED
authors.lastname: Edwards
authors.affiliation: Department of Paediatric Intensive Care, Children's Hospital for Wales, Cardiff, UK.
authors.forename: A
authors.initials: A
authors.lastname: Oliver
authors.affiliation: Department of Child Health, Children's Hospital for Wales, Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Cardiff, UK.
authors.forename: C V E
authors.initials: CVE
authors.lastname: Powell
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003422:Critical Care / Q000706:statistics & numerical data; D016638:Critical Illness / Q000628:therapy*; D004059:Diffusion of Innovation; D006801:Humans; D007223:Infant; D011322:Primary Prevention / Q000379:methods; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D013222:State Medicine / Q000706:statistics & numerical data; D014852:Wales
keywords: General Paediatrics; Health services research