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The interaction of obesity and nocturnal hypoxemia on cardiovascular consequences in adults with suspected obstructive sleep apnea: a historical observational study


Rationale — The inter-relationships between obstructive sleep apnea (OSA) and obesity are complex and bidirectional; however, the current evidence regarding their combined effect o cardiovascular risk is limited and conflicting. Animal studies suggest that obesity may exacerbate the cardiovascular consequences of intermittent hypoxemia.

Objectives — In this historical observational study, we investigated whether obesity increases the effect of nocturnal hypoxemia on the incidence of cardiovascular events in adults with suspected OSA.

Methods — All adults with suspected OSA who underwent diagnostic polysomnography at a large academic hospital between 1994 and 2010 were linked to provincial health administrative data to determine a composite cardiovascular outcome (hospitalization due to heart failure, myocardial infarction, stroke or revascularization procedures). Using a competing-risk model and controlling for confounders, hazards were compared between four groups: (1) obese (BMI>30 kg/m2) with oxygen desaturation (> 9 minutes of sleep spent with SaO2<90%), (2) obese without desaturation, (3) non-obese with desaturation and (4) non-obese without desaturation. Interaction was measured using the relative excess risk due to interaction (RERI).

Measurements and Main Results — 10,149 participants were followed, with 17%, 25%, 8%, and 50% in groups 1 through 4 respectively. Over a median of 7.8 years, 896 (8.8%) first cardiovascular events occurred. Group 1 was associated with the highest hazard as compared to other groups using group 4 as a reference (HR [group 1], 95% CI = 1.84, 1.46-2.32, HR [group 2] =1.59, 1.29-1.95; HR [group 3] =1.51, 1.15-1.98). The RERI was -0.25 (95%CI: -0.78-0.27) indicating no interaction.

Conclusions — In adults with suspected OSA, the highest cardiovascular risk was found in obese patients with nocturnal oxygen desaturation; however, the effect of these two factors together does not exceed the effect of each factor considered individually.



Kendzerska T, Leung RS, Gershon AS, Tomlinson G, Ayas N. Ann Am Thorac Soc. 2016; 13(12):2234-41.

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