Predictors of sleep-disordered breathing and chronic hypoventilation in obese women and men: a cross-sectional observational study

Background and aim Obesity is associated with an increased risk of sleep-disordered breathing (SDB)—obstructive sleep apnoea (OSA) and sleep hypoventilation—and obesity hypoventilation syndrome (OHS). The aim was to assess the impact of obesity on lung volumes and the prevalence of SDB and OHS and to identify predictors of these. Methods In a cross-sectional analysis, obese patients (body mass index ≥30 kg/m $^{2}$ ) who underwent an in-laboratory sleep study, arterial blood gas analysis and pulmonary function tests between 2018 and 2023 were included. Analysis of variance and multivariate regression analysis were used to compare obesity groups and identify predictors of SDB and OHS. Results In 1065 obese adults (39% female; 48% obesity WHO I, 24% WHO II, 28% WHO III), the prevalence of OSA (apnoea hypopnoea index (AHI) ≥5/hour), severe OSA (AHI ≥30/hour), sleep hypoventilation and OHS was 77%, 29%, 21% and 8%, respectively. The likelihood of OSA, severe OSA and sleep hypoventilation increased with obesity class, while the presence of OHS did not differ between groups. In multivariate regression models including body mass index, neck circumference, age, sex, AHI, bicarbonate and expiratory reserve volume, bicarbonate and forced vital capacity were independent predictors of both sleep hypoventilation and OHS and neck circumference of severe OSA. The area under the receiver operating characteristics curve of bicarbonate for OHS and sleep hypoventilation was 0.92 and 0.72, respectively. Conclusions Three quarter of obese patients have OSA, and the likelihood of OSA, severe OSA and sleep hypoventilation increase across obesity severity groups. Bicarbonate has a high diagnostic accuracy for OHS.