Predictive Value of Routine WBC Count Obtained Before Discharge for Organ Space Infection in Children with Complicated Appendicitis: Results from the Eastern Pediatric Surgery Network

BACKGROUND: The objective of this study was to evaluate the clinical utility of a routine predischarge WBC count (RPD-WBC) for predicting postdischarge organ space infection (OSI) in children with complicated appendicitis. STUDY DESIGN: This was a multicenter study using NSQIP-Pediatric data from 14 hospitals augmented with RPD-WBC data obtained through supplemental chart review. Children with fever or surgical site infection diagnosed during the index admission were excluded. The positive predictive value (PPV) for postdischarge OSI was calculated for RPD-WBC values of persistent leukocytosis (≥9.0 × 10³ cells/μL), increasing leukocytosis (RPD-WBC > preoperative WBC), quartiles of absolute RPD-WBC, and quartiles of relative proportional change from preoperative WBC. Logistic regression was used to calculate predictive values adjusted for patient age, appendicitis severity, and use of postdischarge antibiotics. RESULTS: A total of 1,264 children were included, of which 348 (27.5%) had a RPD-WBC obtained (hospital range: 0.8 to 100%, p < 0.01). The median RPD-WBC was similar between children who did and did not develop a postdischarge OSI (9.0 vs 8.9; p = 0.57), and leukocytosis was absent in 50% of children who developed a postdischarge OSI. The PPV of RPD-WBC was poor for both persistent and increasing leukocytosis (3.9% and 9.8%, respectively) and for thresholds based on the quartiles of highest RPD-WBC values (>11.1, PPV: 6.4%) and greatest proportional change (<32% decrease from preoperative WBC; PPV: 7.8%). CONCLUSIONS: Routine predischarge WBC data have poor predictive value for identifying children at risk for postdischarge OSI after appendectomy for complicated appendicitis.