Earlt-to-midlife body mass index trajectories and obstructive sleep apnoea

<bold>Background:</bold> While short-term weight changes are known to influence obstructive sleep apnoea (OSA), the impact of changes in body mass index (BMI) over the life-course was poorly documented. Our aim was to examine the association between BMI trajectories from childhood to middle age and adult OSA. <bold>Methods:</bold> Five BMI trajectories were previously identified in the population-based Tasmanian Longitudinal Health Study (TAHS), using eight time points from age 5 to 43 years. The primary outcome was “probable OSA” at 53 years, defined mainly using STOP-Bang questionnaire. Clinically significant diagnosed OSA at 53 years was defined as having self-reported medical diagnosis or mild OSA with symptoms or moderate-to-severe OSA, using type-4 sleep studies. Associations were examined using multivariable logistic regression. <bold>Results:</bold> Compared with the <italic>average</italic> BMI trajectory, the <italic>child average-increasing</italic> (aOR=5.26, 95% 3.36-8.23) and persistently <italic>high</italic> trajectories (aOR=3.71, 2.06-6.71) were associated with increased risk of probable OSA defined using STOP-Bang. These associations were consistent when using clinically significant diagnosed OSA (<italic>child average-increasi</italic>ng trajectory: aOR=2.95, 1.52-5.70; <italic>high</italic> trajectory: aOR=2.45, 1.14-5.27, separately). Individuals belonging to the <italic>low</italic> were less likely than the <italic>average</italic> trajectory to have OSA. Notably, the <italic>child high-decreasing</italic> trajectory was not associated with OSA. <bold>Conclusion:</bold> Physicians and the public should be aware of the potential for OSA in middle-aged adults when BMI is high or increasing from childhood to middle age. Importantly, obese children who subsequently lose weight are not at higher risk of OSA in middle age-a novel finding and key message.