EFFECT OF BODY MASS INDEX PERCENTILE ON COMPLICATED APPENDICITIS, POSTOPERATIVE COMPLICATIONS AND HEALTH SERVICE UTILIZATION AMONG PEDIATRIC PATIENTS IN THE UNITED STATES

Nutan HEBBALLI, UTHealth School of Public Health

Abstract

While overweight and obesity have been extensively studied for complicated appendicitis, postoperative complications, and health service utilization, the effects of being underweight are unknown. This dissertation assesses the associations between the body mass index (BMI) spectrum with complicated appendicitis, postoperative complications, and healthcare service utilization in pediatric patients. A retrospective review of pediatric patients who underwent appendectomy surgery (01/01/2016-12/31/2020) was conducted using the National Surgical Quality Improvement Program database. Computed age and gender-specific BMI percentiles were categorized into underweight, normal weight, overweight and obese. The 30-day postoperative complications were grouped into minor, major, and any. Healthcare service utilizations were compared across the BMI spectrum using ANOVA. Univariate, multivariable, and negative binomial regression models were performed controlling for patient demographics. The odds of complicated appendicitis were 66% greater in underweight patients (odds ratio (OR)=1.66; 95% confidence interval (CI): 1.06-2.59) and 28% lower in overweight patients (OR=0.72; 95% CI: 0.54-0.95) than normal weight patients. The odds of complicated appendicitis increased due to a statistically significant interaction between preoperative white blood cells (WBC) and obesity (OR=1.02; 95% CI: 1.00-1.03). Compared to normal-weight patients, obese patients had 52% greater odds of minor complications (OR=1.52; 95% CI: 1.18-1.96), and underweight patients had three times the odds of major (OR=2.77; 95% CI: 1.22-6.27) and any complications (OR=2.82; 95% CI: 1.31-6.10). The underweight patients had shorter mean anesthesia duration (90.4±38.6 minutes) and operation time (47.9±23.6 minutes), while the obese patients had longer mean anesthesia duration (98.1±34.4 minutes) and operation time (54.6±27.3 minutes). No significant differences were noted between the BMI categories for unplanned readmissions and unplanned reoperations. The underweight patients had the longest mean length of hospital stay (LOS) (4.0±3.7 days), followed by obese patients (3.8±4.1 days). Both underweight (IRR=1.13; 95%CI: 1.04-1.23) and obese patients had longer LOS than normal-weight patients (IRR=1.06; 95%CI:1.02-1.11). Underweight, overweight, and overweight and preoperative WBC interaction was associated with complicated appendicitis. Obesity, underweight, underweight and preoperative WBC interaction were associated with minor, major, and any complications. Underweight and obese patients were at increased risk for greater health service use. Thus, the BMI spectrum should be considered while managing this patient population.