The Correlation Among Obesity, Apnea-Hypopnea Index, and Tonsil Size in Children

Background The correlation between obesity and severity of obstructive sleep apnea (OSA) is well established in adults, but data are inconsistent in children. We hypothesized that there is a significant correlation between the degree of obesity and the severity of OSA in children. Methods We retrospectively reviewed records of weight, height, history, and polysomnography of all 1-to 15-year-old children referred to our sleep laboratory. Children with known anomalies and repeated polysomnography were excluded from this study. Obesity was defined as body mass index z score (BMI Z score) > 1.96. The correlation between BMI Z score and apnea-hypopnea index (AHI) was assessed. Possible confounding factors, ie , age, gender, and tonsil size, were adjusted by multiple linear regression. Results Four hundred eighty-two children were included in this study. Obese children had a significantly higher AHI (median, 1.5; interquartile range [IQR], 0.2 to 7.0) than the AHI of nonobese children (median, 0.7; IQR, 0.0 to 2.5). BMI Z score was significantly correlated with log-transformed AHI (Ln[AHI]) [ r = 0.156, p=0.003]. BMI Z score and tonsil size were still correlated with Ln(AHI) even after adjusted for other confounding factors (p = 0.001). Conclusion Degree of obesity as measured by BMI Z score and tonsil size are significantly related to severity of OSA as reflected by the AHI, although the correlation is mild.