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.”