Background: Childhood obstructive sleep apnoea (OSA) is increasingly being recognized. Its effect on blood pressure (BP) elevation and hypertension is still controversial.
Objective: To evaluate the association between obstructive sleep apnoea and ambulatory BP in children.
Methods: Children aged 6 to 13 years from randomly selected schools were invited to undergo overnight sleep study and ambulatory BP monitoring after completing a validated OSA questionnaire. OSA was diagnosed if obstructive apnoea-hypopnoea index (AHI) > 1, and normal controls had AHI < 1 and snoring < 3 nights per week. Children with OSA were sub-stratified into mild group (AHI between 1 and 5) and moderate-to-severe group (AHI > 5).
Results: Three hundred and six subjects had valid sleep and daytime BP data. Children with OSA had significantly higher blood pressure than normal healthy children during both sleep and wakefulness. The BP levels increased with the severity of OSA, and children with moderate-to-severe disease (AHI > 5) were at significantly higher risk for nocturnal systolic (OR = 3.9 [95% CI: 1.4-10.5]) and diastolic hypertension (OR = 3.3 [95% CI: 1.4-8.1]). Multiple linear regression revealed a significant association between oxygen desaturation index and AHI with daytime and nocturnal BP respectively independent of obesity.
Conclusions: OSA was associated with elevated daytime and nocturnal BP, and it is an independent predictor of nocturnal hypertension. This has important clinical implications as childhood elevated BP predicts future cardiovascular risks. Future studies should examine the effect of therapy for OSA on BP changes.