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20-11-2011 | Cardiology | Article

Obstructive sleep apnea worsens metabolic impairment in morbid obesity


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MedWire News: Obstructive sleep apnea (OSA) is linked to major metabolic impairment in morbidly obese patients due to increased blood pressure and poor lipid and glucose control, regardless of central obesity or the presence of diabetes, say Spanish scientists.

Metabolic abnormalities, which increase cardiovascular morbidity and mortality, are associated with central obesity. However, other mechanisms have been proposed, and there is evidence to suggest that OSA may worsen the impact of obesity on cardiometabolic risk, they explain.

Believing that morbidly obese patients with OSA have greater impairment of the metabolic profile than morbidly obese patients without OSA, Mercè Gasa, from Hospital Universitari de Bellvitge in Hospitalet de Llobregat, and colleagues conducted a multicenter, cross-sectional study of 159 patients undergoing bariatric surgery.

The team reports in the European Respiratory Journal that 72% of the patients had OSA, defined as an apnea/hypopnoea index (AHI) of at least 15 using overnight polysomnography.

The prevalence of the metabolic syndrome, diagnosed using the National Cholesterol Education Program Adult Treatment Panel III modified criteria, was significantly higher in OSA versus non-OSA patients, at 70% versus 36%, corresponding to an adjusted odds ratio of 2.8.

OSA patients were significantly more likely to have hypertension than non-OSA patients, at 48% versus 21%, respectively, and more likely to have Type 2 diabetes, at 24% versus 11%, respectively.

Even in patients without Type 2 diabetes, metabolic parameters progressively worsened with increasing AHI. Further analysis demonstrated that AHI was independently associated with systolic and diastolic blood pressure, triglycerides, and the percentage of glycated hemoglobin (HbA1c). In addition, in patients without Type 2 diabetes, AHI was associated with systolic blood pressure, high-density lipoprotein cholesterol, and HbA1c.

The team concludes: "OSA is associated with a more severe metabolic profile in morbidly obese patients, independent of age, sex, [body mass index], and smoking, suggesting an important role of OSA, in addition to obesity, in the pathogenesis of metabolic dysfunction in this population.

"As OSA is a treatable condition, and excessive daytime sleepiness assessed by [the] Epworth sleepiness scale is not a good OSA marker in morbid obesity, clinicians dealing with obese subjects should appropriately assess OSA in addition to other classic known obesity-related comorbidities, in order to better treat the overall metabolic dysfunction," the researchers advise.

By Liam Davenport

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