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Pediatrics. 2005 Sep;116(3):709-16.

A clinical decision rule to identify children at low risk for appendicitis.

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  • 1Division of Emergency Medicine, Children's Hospital Boston, Harvard Medical School, Boston, MA, USA. ak493@columbia.edu



Computed tomography (CT) has gained widespread acceptance in the evaluation of children with suspected appendicitis. Concern has been raised regarding the long-term effects of ionizing radiation. Other means of diagnosing appendicitis, such as clinical scores, are lacking in children. We sought to develop a clinical decision rule to predict which children with acute abdominal pain do not have appendicitis.


Prospective cohort study was conducted of children and adolescents who aged 3 to 18 years, had signs and symptoms suspicious for appendicitis, and presented to the emergency department between April 2003 and July 2004. Standardized data-collection forms were completed on eligible patients. Two low-risk clinical decision rules were created and validated using logistic regression and recursive partitioning. The sensitivity, negative predictive value (NPV), and negative likelihood ratio of each clinical rule were compared.


A total of 601 patients were enrolled. Using logistic regression, we created a 6-part score that consisted of nausea (2 points), history of focal right lower quadrant pain (2 points), migration of pain (1 point), difficulty walking (1 point), rebound tenderness/pain with percussion (2 points), and absolute neutrophil count of >6.75 x 10(3)/microL (6 points). A score < or =5 had a sensitivity of 96.3% (95% confidence interval [CI]: 87.5-99.0), NPV of 95.6% (95% CI: 90.8-99.0), and negative likelihood ratio of .102 (95% CI: 0.026-0.405) in the validation set. Using recursive partitioning, a second low-risk decision rule was developed consisting of absolute neutrophil count of <6.75 x 10(3)/microL, absence of nausea, and absence of maximal tenderness in the right lower quadrant. This rule had a sensitivity of 98.1% (95% CI: 90.1-99.9), NPV of 97.5% (95% CI: 86.8-99.9), and negative likelihood ratio of 0.058 (95% CI: 0.008-0.411) in the validation set. Theoretical application of the low-risk rules would have resulted in a 20% reduction in CT.


Our low-risk decision rules can predict accurately which children are at low risk for appendicitis and could be treated safely with careful observation rather than CT examination.

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