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Question clinique
Can a combination of clinical features and laboratory values rule out acute appendicitis in children?
L’Essentiel
The Pediatric Appendicitis Laboratory Score (PALabS), a score that combines clinical features and laboratory values, is accurate in ruling out acute appendicitis in children. 1b
Référence
Plan de l'etude: Decision rule (validation)
Financement: Self-funded or unfunded
Cadre: Emergency department
Sommaire
These authors prospectively enrolled children 2 years to 14 years of age who visited a single emergency department for suspected appendicitis. The research team gathered clinical and laboratory data in a structured manner. From the 361 children they enrolled, the authors randomly selected 278 to develop a clinical prediction rule, and then validated the rule on a mixed cohort of the 83 remaining children an additional 172 children seen in the same emergency department during an earlier time frame. The diagnosis of appendicitis was confirmed using pathology for those undergoing surgery and clinical follow-up 15 days after the index visit. Clouding the picture a bit, the authors also used ultrasound during the diagnostic process. Among the children in the derivation cohort, 35.9% had acute appendicitis compared with 49% in the validation group. After performing feats of statistical gymnastics, the authors created the PALabS, which consists of 6 parts: nausea (3 points), maximal pain in the right lower quadrant (4 points), absolute neutrophil count above 7500 per microliter (7 points), white blood cell count above 10,000 per microliter (4 points), C-reactive protein above 10 mg per liter (2 points), and calprotectin above 50 nanograms per milliliter (3 points). Overall, in the derivation group, the PALabS was accurate (area under the receiver operator characteristic curve 0.88). The researchers also applied 2 other scores to the derivation sample, the Pediatric Appendicitis Score and the Kharbanda Score. They found these scores to have less diagnostic accuracy. In the validation cohort, a PALabS of 6 or less was 99.2% sensitive (95% CI 95.6 - 99.9) and had a negative likelihood ratio of 0.03 (0.00 - 0.18). Although the authors did not report the specificity of the PALabS, based on my calculations, it was approximately 32% and the positive likelihood ratio was 3.2. In other words, this looks like a SnNOut (a very sensitive test that rules out the disease when the result result is negative). Now this clincial prediction rule needs to be tested in an independent cohort of patients.
Reviewer
Henry C. Barry, MD, MS
Professor
Michigan State University
East Lansing, MI