Objectives: To determine the incidence of obstructive sleep apnea syndrome in children aged 2 to 4 years with Down syndrome and to determine parents' ability to predict sleep abnormalities in this patient population.
Design: Prospective cohort study.
Setting: Tertiary care pediatric referral center.
Patients: Sixty-five children participating in a 5-year longitudinal study in which the otolaryngologic problems seen in Down syndrome were evaluated. Fifty-six completed overnight polysomnography (PSG) between 4 and 63 months of age (mean age, 42 months).
Interventions: Overnight PSG was performed. Parents also completed a questionnaire regarding their impressions of their child's sleep patterns before PSG.
Main outcome measures: Polysomnograms were classified as abnormal if the obstructive index was greater than 1, if the carbon dioxide level was greater than 45 mm Hg for more than two thirds of the study or greater than 50 mm Hg for more than 10% of the study, and/or if there was unexpected hypoxemia less than 92% during sleep or repeated intermittent desaturations less than 90%. We also identified a group of children whose PSGs findings were normal except for an arousal index greater than 10 and were associated with increased work of breathing.
Results: The PSGs revealed that 57% of the children had abnormal results and evidence of obstructive sleep apnea syndrome. If we also include an elevated arousal index, 80% of the PSGs had abnormal results. Sixty-nine percent of parents reported no sleep problems in their children, but in this group, 54% of PSGs had abnormal results. Of the parents who reported sleep problems in their children, only 36% had abnormal sleep study results.
Conclusion: Because of the high incidence of obstructive sleep apnea syndrome in young children with Down syndrome, and the poor correlation between parental impressions of sleep problems and PSG results, baseline PSG is recommended in all children with Down syndrome at age 3 to 4 years.