Risk factors for sleep-related hypoxia in primary school children.
Sleep-related hypoxia has adverse effects on cognition in children. Knowledge of factors contributing to sleep-related hypoxia is sparse. We aimed to identify demographic and clinical factors associated with mild (nadir arterial oxygen saturation 91-93%), moderate (nadir arterial oxygen saturation <or=90%), and recurrent (oxygen desaturation index > 3.9) sleep-related hypoxia in children. Parental questionnaires were distributed and overnight recordings of arterial oxygen saturation performed in a population-based cross-section of primary school children (n = 995). Associations were determined using unconditional logistic regression as well as unadjusted and adjusted odds ratios (OR), and their 95% confidence intervals (95% CI) calculated. Male sex, overweight (i.e., body mass index >or= 75th percentile), household smoking, symptoms of sleep-disordered breathing, a current respiratory tract infection, and histories of asthma and respiratory allergy were all significantly associated with sleep-related hypoxia. In multiple regression analysis, (i) overweight (OR, 95% CI: 2.7, 1.7-4.3) and a history of respiratory allergy (1.7, 1.1-2.7) were independent risk factors for mild sleep-related hypoxia, (ii) overweight (3.2, 1.7-5.8), a history of respiratory allergy (2.4, 1.4-4.4), and household smoking >10 cigarettes/day (1.8, 1.1-2.8) were independent risk factors for moderate sleep-related hypoxia, and (iii) overweight (2.3, 1.04-5.3), a history of respiratory allergy (2.5, 1.2-5.1), and a current respiratory tract infection (4.4, 2.0-9.8), were independent risk factors for recurrent sleep-related hypoxia. Our data suggest that overweight, passive smoking, respiratory allergies, and acute lung disease may independently contribute to sleep-related hypoxia in children.