Methods
This was a retrospective cohort study using the American College of Surgeons National Surgical Quality Improvement Program-Pediatric (NSQIP-P) database (2012-2017). The NSQIP-P is a multi-institutional, multispecialty, clinical surgical outcomes database that includes a sampling of cases by most pediatric surgical specialties up to 30 days after a surgical procedure (excluding trauma and transplant cases) in patients younger than 18 years of age. Data for the NSQIP-P are collected in 8-day cycles for a select group of surgical procedures. These data include patient demographics, preoperative laboratory values, preoperative risk factors, Current Procedural Terminology codes for the procedure performed, operative details and 30-day complications.
We included patients ≤18 years undergoing appendectomy. Patient variables included age, gender, pre-operative WBC, whether or not the patient had current chemotherapy treatment or active cancer diagnosis, laparoscopic vs open appendectomy, and perforated vs non-perforated appendicitis. WBC counts were grouped by following the National Cancer Institute’s common terminology criteria for adverse events: grade 1 leukopenia as ≥3000/mm3, grade 2 as 2000-<3 000/mm3, grade 3 as 1000-<2 000/mm3, and grade 4 as <1000/mm3. The primary outcomes of interest were 30-day wound complications (superficial or deep infections or dehiscence, and abscess). Pearson’s χ2 and two sample t tests were used to compare outcomes in a univariate analysis; multivariable logistic regression was used to calculate odds of complications. Additionally, a sensitivity analysis was performed by repeating the multivariable logistic regression on only patient records that had a preoperative WBC count.
Readmission rates were calculated using NSQIP flags for hospital readmission within 30 days of operation, while reasons for readmission were assessed using the NSQIP flag for “readmission related to surgery.”