Obesity and respiratory complications after pediatric adenotonsillectomy: A national analysis of effect modification by high-risk comorbidities.

OBJECTIVE: To evaluate the association between obesity and perioperative respiratory adverse events (PRAEs) in children undergoing ambulatory adenotonsillectomy, tonsillectomy, or adenoidectomy, and to assess whether high-risk comorbidities modify this association. METHODS: Retrospective cross-sectional analysis of the Healthcare Cost and Utilization Project Nationwide Ambulatory Surgery Sample (NASS), 2016-2022. All encounters for patients younger than 18 years undergoing these procedures were included. Obesity and PRAEs were identified by ICD-10-CM diagnosis codes. Survey-weighted logistic regression estimated adjusted odds ratios (aORs) controlling for age, sex, comorbidities, payer, income quartile, hospital characteristics, and calendar year. Interaction terms tested effect modification by Down syndrome, congenital heart disease, craniofacial anomalies, asthma, sickle cell disease, and thalassemia. RESULTS: Among 1 495 718 unweighted encounters (1 997 730 weighted), 65 983 (3.30%) carried an obesity diagnosis. PRAEs occurred in 0.77% of obese versus 0.59% of non-obese children (p < .001). Unadjusted, obesity was associated with 31% higher PRAE odds (OR, 1.31; 95% CI, 1.14-1.50). After adjustment for age, sex, and clinical comorbidities, the association strengthened due to negative confounding by age (aOR, 1.85; 95% CI, 1.62-2.12) and remained significant in the fully adjusted model (aOR, 1.62; 95% CI, 1.42-1.86). A sub-multiplicative obesity-asthma interaction was identified (p = .009): the observed combined effect (OR, 2.07) fell below the expected multiplicative joint effect of 2.89. No other significant interactions emerged. CONCLUSION: Obesity independently elevated PRAE risk in this national ambulatory cohort. The sub-multiplicative obesity-asthma interaction indicates partially overlapping risk pathways and supports a lower threshold for extended postoperative observation in obese children with comorbid asthma.