Prediagnostic antibiotic use and its association with results of false-negative pediatric appendicitis scores: A single-center retrospective cohort study

In facilities with limited pediatric imaging or surgical treatment, the pediatric appendicitis score (PAS) is widely used to support referral or transfer decisions. However, false-negative PAS results may delay diagnosis and increase the risk of complications. We aimed to identify factors associated with false-negative PAS results, focusing on the effect of prediagnostic antibiotic use. This retrospective cohort study comprised pediatric patients aged ≤15 years who had undergone appendectomy for pathologically confirmed appendicitis between April 2013 and March 2023 at a single tertiary care center in Japan. The patients were divided into low- (PAS ≤6) or high- (PAS ≥7) PAS groups. Clinical characteristics were compared and logistic regression analysis was performed. Among 274 eligible patients, 69 (25.1 %) had a PAS of ≤6. Prediagnostic antibiotic use was significantly more common in this group, and logistic regression analysis identified antibiotic use as an independent predictor of a low PAS (odds ratio: 15.5). Patients who received prediagnostic antibiotic therapy showed lower rates of leukocytosis and neutrophilia, delayed presentation, and higher rates of perforation and gangrenous appendicitis. Prediagnostic antibiotic use may reduce PAS and delay diagnosis. Appropriate imaging or surgery, when indicated, should not be delayed even in children with a low PAS after antibiotic exposure. Clinicians should also consider referral when prior antibiotics and a low PAS cause diagnostic uncertainty.