Objectives: To assess the cardiovascular outcomes of children with obstructive sleep apnoea (OSA) at a mean of 5 years after they had undergone adenotonsillectomy (AT), compared to OSA children who did not undergo AT, and normal controls without OSA. Hypothesis to be tested: (1) children with OSA underwent AT would have lower cardiovascular risks, namely lower ambulatory blood pressure (ABP), better cardiac function, lower carotid intima-media thickness (CIMT) and lower carotid arterial thickness when compared to those with OSA but did not undergo AT, and that (2) children with OSA, despite treatment with AT, would have higher cardiovascular risks than non-OSA controls.

Design: A two-centre prospective case-control follow-up study Subjects: Potential subjects for this follow-up study have been identified from two local hospitals, Prince of Wales and Kwong Wah Hospitals. AT-treated group (n=90) - Children had moderate-to-severe OSA (obstructive apnoea hypopnoea index (OAHI) \>=3 events/h) and underwent AT when they were aged 5-12 years. Refused AT group (n=45) - Children had moderate-to-severe OSA but refused AT. Non-OSA control group (n=45) - Non-snoring controls with OAHI \<1 event/h . Main outcome measures: 24-hour ABP, cardiac function measured by echocardiography, CIMT and carotid arterial stiffness. Data analysis: Apart from group comparisons, multiple linear regression and logistic regression analysis will also be used to examine whether cardiovascular outcomes are associated with AT, pre- and post-AT OAHI while adjusted for confounders. Expected results: AT improves cardiovascular outcomes of children with OSA. However they still had higher cardiovascular risks than normal controls even after AT.