0502 RELATIONSHIP BETWEEN ANTHROPOMETRIC PARAMETERS AND OBSTRUCTIVE SLEEP APNEA IN SCHOOL AGE CHILDREN

Pediatric obstructive sleep apnea (OSA) is more common in obese children. However, the role of fat distribution in the pathogenesis of OSA in this age group is controversial. We evaluated the association of OSA to excess adiposity and abdominal fat. We hypothesized a positive correlation between anthropometric parameters and OSA and an inverse correlation between obesity and the oxyhemoglobin saturation (SpO2) nadir in a large sample of school-aged children with OSA. We investigated the baseline data from the childhood adenotonsillectomy trial (CHAT). The relationship between apnea hypopnea index (AHI), SpO2 nadir, peak CO2 during sleep and body-mass index Z-score (BMI z-score), waist:height ratio (WTHR) and neck:height ratio (NHR) was evaluated. AHI was evaluated using linear regression in log scale which improved its distribution towards normal. Other outcomes were evaluated using Spearman correlations. 452 children were analyzed (52% girls). The mean ± SD age was 7 ± 1.4years. The mean BMI Z-score was 0.8 ± 1.3. There was a positive correlation between log AHI and BMI Z-score (β=0.06, r=0.10, p=0.03) and WTHR; (β=1.00, r=0.10, p=0.03), and an inverse correlation between SpO2 nadir and BMI z-score (r=-0.19, p=0.00005), and WTHR (r=-0.17, p=0.0002) and NHR (r=-0.12, p=0.008). When corrected for multiple comparisons, there remained an inverse correlation between SpO2 nadir and BMI z-score and SpO2 nadir and WTHR. BMI Z-score and WTHR, an index of visceral fat, correlate with the degree of desaturation during sleep in school-age children. However, in contrast to adults, anthropometric measures do not correlate with indices of upper airway obstruction such as the AHI. We speculate that restrictive lung disease and a lower pulmonary reserve in obese children predisposes to deeper oxyhemoglobin desaturation with obstructive events. Funded by the National Institutes of Health; CHAT ClinicalTrials.gov number, NCT00560859.