M. Macrae1, S. Patel1, S. Berlin4, T. McCallin3, E. Miyasaka2 1Case Western Reserve University School Of Medicine, Cleveland, OH, USA 2University Hospitals, Pediatric Surgery, Cleveland, OH, USA 3University Hospitals, Pediatric Emergency Medicine, Cleveland, OH, USA 4University Hospitals, Pediatric Radiology, Cleveland, OH, USA
Introduction: Numerous scoring systems exist to aid in the clinical diagnosis of appendicitis. Previous retrospective data has shown that the addition of C-reactive protein (CRP) into the pediatric appendicitis score (PAS) increased identification of patients at low risk for acute appendicitis compared to PAS alone. As part of a multidisciplinary process improvement program, our institution implemented a protocol to routinely obtain CRP in patients presenting to the emergency department (ED) for evaluation of abdominal pain suspicious for acute appendicitis. The primary objective of this study is to prospectively validate the PAS+CRP risk stratification tool to identify a group that is truly low risk for appendicitis who may be safely discharged from the ED.
Methods: A new diagnostic protocol for acute appendicitis in which CRP was routinely obtained in addition to labs necessary to calculate PAS was implemented in June 2023 at a single pediatric ED. From the start of this protocol through June 2024, 146 patients presented with abdominal pain in which acute appendicitis was considered in the differential diagnosis. A PAS+CRP was calculated for all patients by adding 1 point to the traditional PAS for CRP > 0.1 mg/dL, and 2 points if CRP was > 1 (total score 0-12). Patients with a score of 0-5 were categorized as low risk, 6-8 moderate risk, and 9-12 high risk. Rates of missed appendicitis and risk stratification were compared to rates at our institution prior to the protocol implementation (2017-2021). Descriptive statistics were obtained and comparisons between groups were done using chi-squared and Fisher exact tests.
Results: All patients evaluated during this period had CRP values obtained compared to 87% pre-protocol (p<0.0002). PAS+CRP identified 17% more patients as low risk compared to the traditional PAS (54% vs 37%, p=0.003) and risk stratification breakdown is shown in Table 1. The rate of missed appendicitis in the low-risk group was 3.8% which was similar to the pre-protocol rate of 1.9% (p=0.342). The rate of true appendicitis in the moderate and high-risk groups remained low (8.3% to 21.8%).
Conclusion: Our findings validated the use of PAS+CRP to safely identify patients at low risk for acute appendicitis. However, the rate of true appendicitis was low in the moderate and high risk patients, highlighting the need for better patient selection methods when applying PAS to rule in appendicitis.