LAUSR

OBJECTIVES Children with obstructive sleep apnea (OSA) who undergo adenotonsillectomy (AT) often experience post-operative weight gain, although the mechanism remains unclear. Our aim is to understand how changes in sleep events impact changes in weight in children with OSA following adenotonsillectomy compared to watchful waiting with supportive care. METHODS We performed a secondary analysis of the Childhood adenotonsillectomy trial (CHAT) dataset in which children with OSA were randomized to undergo early adenotonsillectomy (eAT) or watchful waiting with supportive care (WWSC). The primary outcome measures included changes in body mass index (BMI) percentile, apnea-hypopnea index (AHI) and arousal index (AI) during rapid eye movement (REM) sleep. The change in BMI percentile attributable to changes in AHI and AI during REM sleep was determined using causal mediation analysis. RESULTS Of the 453 children with OSA randomized to eAT or WWSC, 397 children were included in the analysis. Children in the eAT arm experienced a greater increase in their weight as measured by BMI percentile, compared to children who received WWSC (WWSC 4.12 (2.70, 5.55) vs. eAT 6.62 (4.87, 8.38), Cohen's d = 0.22 (0.02, 0.42), p = 0.02). A significant proportion of the weight gain was attributable to decreases in apneic events (proportion mediated 19% (2-97%), p = 0.03) and arousals (proportion mediated 20% (5-78%), p = 0.01) during REM sleep. CONCLUSION A significant proportion of post-adenotonsillectomy weight gain in children with OSA is attributable to polysomnographic changes during REM sleep, potentially due to the mitigation of REM-related sleep fragmentation and subsequent reduction in metabolic expenditure.