Clinical Features and Preventability of Delayed Diagnosis of Pediatric Appendicitis.

Importance: Delayed diagnosis of appendicitis is associated with worse outcomes than timely diagnosis, but clinical features associated with diagnostic delay are uncertain, and the extent to which delays are preventable is unclear. Objective: To determine clinical features associated with delayed diagnosis of pediatric appendicitis, assess the frequency of preventable delay, and compare delay outcomes. Design, Setting, and Participants: This case-control study included 748 children treated at 5 pediatric emergency departments in the US between January 1, 2010, and December 31, 2019. Participants were younger than 21 years and had a diagnosis of appendicitis. Exposures: Individual features of appendicitis and pretest likelihood of appendicitis were measured by the Pediatric Appendicitis Risk Calculator (pARC). Main Outcomes and Measures: Case patients had a delayed diagnosis of appendicitis, defined as 2 emergency department visits leading to diagnosis and a case review showing the patient likely had appendicitis at the first visit. Control patients had a single emergency department visit yielding a diagnosis. Clinical features and pARC scores were compared by case-control status. Preventability of delay was assessed as unlikely, possible, or likely. The proportion of children with indicated imaging based on an evidence-based cost-effectiveness threshold was determined. Outcomes of delayed diagnosis were compared by case-control status, including hospital length of stay, perforation, and multiple surgical procedures. Results: A total of 748 children (mean [SD] age, 10.2 [4.3] years; 392 boys [52.4%]; 427 White children [57.1%]) were included in the study; 471 (63.0%) had a delayed diagnosis of appendicitis, and 277 (37.0%) had no delay in diagnosis. Children with a delayed diagnosis were less likely to have pain with walking (adjusted odds ratio [aOR], 0.16; 95% CI, 0.10-0.25), maximal pain in the right lower quadrant (aOR, 0.12; 95% CI, 0.07-0.19), and abdominal guarding (aOR, 0.33; 95% CI, 0.21-0.51), and were more likely to have a complex chronic condition (aOR, 2.34; 95% CI, 1.05-5.23). The pretest likelihood of appendicitis was 39% to 52% lower in children with a delayed vs timely diagnosis. Among children with a delayed diagnosis, 109 cases (23.1%) were likely to be preventable, and 247 (52.4%) were possibly preventable. Indicated imaging was performed in 104 (22.0%) to 289 (61.3%) children with delayed diagnosis, depending on the imputation method for missing data on white blood cell count. Patients with delayed diagnosis had longer hospital length of stay (mean difference between the groups, 2.8 days; 95% CI, 2.3-3.4 days) and higher perforation rates (OR, 7.8; 95% CI, 5.5-11.3) and were more likely to undergo 2 or more surgical procedures (OR, 8.0; 95% CI, 2.0-70.4). Conclusions and Relevance: In this case-control study, delayed appendicitis was associated with initially milder symptoms but worse outcomes. These findings suggest that a majority of delayed diagnoses were at least possibly preventable and that many of these patients did not undergo indicated imaging, suggesting an opportunity to prevent delayed diagnosis of appendicitis in some children.