title: Validation and refinement of a prediction rule to identify children at low risk for acute appendicitis.
abstract: OBJECTIVE
  To validate and refine a clinical prediction rule to identify which children with acute abdominal pain are at low risk for appendicitis (Low-Risk Appendicitis Rule).
  
  
  METHODS
  Prospective, multicenter, cross-sectional study.
  
  
  METHODS
  Ten pediatric emergency departments.
  
  
  METHODS
  Children and adolescents aged 3 to 18 years who presented with suspected appendicitis from March 1, 2009, through April 30, 2010.
  
  
  METHODS
  The test performance of the Low-Risk Appendicitis Rule.
  
  
  RESULTS
  Among 2625 patients enrolled, 1018 (38.8% [95% CI, 36.9%-40.7%]) had appendicitis. Validation of the rule resulted in a sensitivity of 95.5% (95% CI, 93.9%-96.7%), specificity of 36.3% (33.9%-38.9%), and negative predictive value of 92.7% (90.1%-94.6%). Theoretical application would have identified 573 (24.0%) as being at low risk, misclassifying 42 patients (4.5% [95% CI, 3.4%-6.1%]) with appendicitis. We refined the prediction rule, resulting in a model that identified patients at low risk with (1) an absolute neutrophil count of 6.75 × 103/μL or less and no maximal tenderness in the right lower quadrant or (2) an absolute neutrophil count of 6.75 × 103/μL or less with maximal tenderness in the right lower quadrant but no abdominal pain with walking/jumping or coughing. This refined rule had a sensitivity of 98.1% (95% CI, 97.0%-98.9%), specificity of 23.7% (21.7%-25.9%), and negative predictive value of 95.3% (92.3%-97.0%).
  
  
  CONCLUSIONS
  We have validated and refined a simple clinical prediction rule for pediatric appendicitis. For patients identified as being at low risk, clinicians should consider alternative strategies, such as observation or ultrasonographic examination, rather than proceeding to immediate computed tomographic imaging.
authors.affiliation: Department of Pediatrics Columbia University College of Physicians and Surgeons, New York, New York, USA. anupam.kharbanda@childrensmn.org
authors.forename: Anupam B
authors.initials: AB
authors.lastname: Kharbanda
authors.forename: Nanette C
authors.initials: NC
authors.lastname: Dudley
authors.forename: Lalit
authors.initials: L
authors.lastname: Bajaj
authors.forename: Michelle D
authors.initials: MD
authors.lastname: Stevenson
authors.forename: Charles G
authors.initials: CG
authors.lastname: Macias
authors.forename: Manoj K
authors.initials: MK
authors.lastname: Mittal
authors.forename: Richard G
authors.initials: RG
authors.lastname: Bachur
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Bennett
authors.forename: Kelly
authors.initials: K
authors.lastname: Sinclair
authors.forename: Craig
authors.initials: C
authors.lastname: Huang
authors.forename: Peter S
authors.initials: PS
authors.lastname: Dayan
mesh_terms: D015746:Abdominal Pain / Q000209:etiology*; D000208:Acute Disease; D000293:Adolescent; D001064:Appendicitis / Q000150:complications / Q000175:diagnosis*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D003661:Decision Support Techniques; D003937:Diagnosis, Differential; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies; D015203:Reproducibility of Results; D012306:Risk; D012680:Sensitivity and Specificity