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Decision rule identifies kids at low risk of appendicitis

Clinical Question:
How reliable is a clinical decision rule at identifying children at low risk of appendicitis?

Bottom Line:
A simple decision rule using a combination of abdominal examination findings and white blood cell count is accurate in identifying children at low risk of having appendicitis. Since the rule is not perfect, you still need to use some clinical judgment to decide if you want to perform an ultrasound or just observe the low-risk child. (LOE = 1b)

Kharbanda AB, Dudley NC, Bajaj L, et al., for the Pediatric Emergency Medicine Collaborative Research Committee of the American Academy of Pediatrics. Validation and refinement of a prediction rule to identify children at low risk for acute appendicitis. Arch Pediatr Adolesc Med 2012;166(8):738-744.  [PMID:22869405]

Study Design:
Decision rule (validation)


Emergency department

These researchers, in 10 pediatric emergency departments, evaluated children aged 3 to 18 years with acute abdominal pain of less than 96 hours duration and undergoing evaluation for suspected appendicitis. Trained investigators at each site completed a standardized assessment of each patient. To assess interobserver reliability, a subset of patients received a second independent assessment within 30 to 60 minutes of the initial evaluation. The authors are not explicit about this, but it appears they used a composite gold standard based on (1) the pathologist’s report for kids undergoing surgery, and (2) parental report 2 weeks after discharge from the emergency department. Additionally, the researchers reviewed the medical records of the kids whose parents they weren't able to reach. Overall, they had complete data on nearly 2400 patients, 91% of those enrolled. The final model identified children as being at low risk of appendicitis if they met one of the following criteria: (1) absolute neutrophil count no more than 6750/microliter and no right lower quadrant tenderness; OR (2) absolute neutrophil count no more than 6750/microliter with maximal tenderness in the right lower quadrant but no abdominal pain with walking, jumping, or coughing. This model was 98% sensitive and 24% specific. In other words, it is very good at identifying children at low risk of appendicitis.


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