Body mass index as an indicator of obstructive sleep apnea in pediatric Down syndrome

ObjectiveOur objective was to determine if higher body mass index (BMI) increases the likelihood of, obstructive sleep apnea (OSA) in pediatric Down syndrome (DS) patients.MethodsWe performed a, retrospective chart review of 63 DS patients evaluated by overnight polysomnography from December 1995 to February 2005. Patients aged less than 2 years were excluded. Remaining patients were grouped, according to presence (n = 19) or absence (n = 33) of OSA based on apnea hypopnea index (AHI). OSA, and non-OSA DS groups were age matched while blinded to patient attributes other than age and OSA, status. Patients without appropriate age matches were excluded. We recorded various patient information, including age, sex, height, weight, number of apneas, number of hypopneas, respiratory distress index (RDI), apnea–hypopnea index (AHI), lowest oxygen saturation during sleep, mean oxygen saturation, number of arousals per hour, and mean time spent in REM sleep. We calculated BMI using the, standard kg/m2 formula and converted this into a Z-score.ResultsFifty-two DS patients were analyzed with average age of 9.3 ± 4.5 years (10.2 ± 4.2 in 33 OSA patients, 7.8 ± 4.3 in 19 non-OSA patients). There were 28 males and 24 females. The OSA group mean BMI Z-score was 2.09 ± 0.94, and the non-OSA group Z-score was 1.4 ± 1.40. The Z-scores for BMI were statistically significant between OSA and non-OSA patients with p = 0.03 by t-test.ConclusionsWhen age and sex adjusted, BMI has a statistically significant association with the presence of OSA in Down syndrome patients. The incidence of OSA also increases with increasing age in this population.