The relationship between BMI and pediatric postoperative outcomes: a 12-year NSQIP-P analysis.

BACKGROUND

Childhood obesity is increasingly prevalent and historically considered a risk factor for surgical complications. Evaluating the influence of body mass index (BMI) on pediatric surgical outcomes is critical for guiding care. This study aimed to examine the relationship between BMI and postoperative outcomes in children.

METHODS

Cohort study of patients aged 2-18 years undergoing general surgical, urological, or gynecological procedures at National Surgical Quality Improvement Program-Pediatric hospitals (2012-2023). The exposure was BMI categories defined by American Academy of Pediatrics and Centers for Disease Control and Prevention. The primary outcome was the Desirability of Outcome Ranking (DOOR), a composite measure of 22 postoperative events ranked from 1 (no complication) to 6 (worst complications). Ordinal logistic regression models, adjusted for clinical risk, assessed the association between BMI and DOOR.

RESULTS

Among 373,315 patients (mean age 10.8 ± 4.7 years; 54.2% male), 7.1% were underweight, 55.1% normal weight, 15.1% overweight, 12.3% class I obesity, 6.0% class II obesity, and 4.3% class III obesity. Unadjusted analyses showed fewer complication-free courses (DOOR score 1) in underweight children, while class II-III obesity had the highest proportion of complication-free courses. In adjusted analyses, underweight was associated with worse DOOR scores (OR 1.08, 95% CI 1.04-1.12) while Class II (OR 0.89, 95% CI 0.85-0.94) and class III obesity (OR 0.76, 95% CI 0.71-0.81) were protective. Subgroup analyses showed that in elective general surgery, class II (OR 0.79, 95% CI 0.73-0.86) and class III obesity (OR 0.65, 95% CI 0.59-0.72) remained protective, whereas in non-elective general surgery, underweight status was still predictive of worse DOOR scores (OR 1.25, 95% CI 1.16-1.34).

CONCLUSION

Extremely low BMI was consistently linked to less desirable postoperative outcomes, whereas obesity was paradoxically associated with more favorable DOOR scores. Elevated BMI alone should not be considered a contraindication to pediatric surgery. Efforts to optimize underweight children may offer the greatest opportunity to improve surgical outcomes.