Protective cardiovascular effect of sleep apnea severity in obesity hypoventilation syndrome

Abstract

Background: Obesity hypoventilation syndrome (OHS) is associated with a high burden of cardiovascular morbidity (CVM) and mortality. The majority of OHS patients have concomitant obstructive sleep apnea (OSA), but there is a paucity of data on the association between CVM and OSA severity in patients with OHS. The objective of our study was to assess the association between CVM and OSA severity in a large cohort of patients with OHS. Methods: In a cross-sectional analysis, we examined the association between OSA severity based on tertiles of oxygen desaturation index (ODI) and CVM in 302 patients with OHS. Logistic regression models were constructed to quantify the independent association between OSA severity and prevalent CVM after adjusting for various important confounders. Results: In unadjusted analysis, the prevalence of CVM decreased significantly with increasing severity of OSA based on ODI tertiles. This inverse relationship between OSA severity and prevalence of CVM persisted despite adjustment for multiple confounders. Chronic heart failure had the strongest negative association with ODI tertiles. Patients in the highest ODI tertile were younger, predominantly male, more obese, more hypersomnolent, had worse gas exchange, lower prevalence of hypertension, and better exercise tolerance than patients in the lower ODI tertiles. Conclusion: In OHS patients, higher OSA severity as measured by intermittent hypoxemia is associated with reduced prevalence of CVM. This finding should guide the design of future clinical trials assessing the impact of interventions aimed at decreasing cardiovascular morbidity and mortality in patients with OHS.