The Impact of Obstructive Sleep Apnea on Metabolic and Inflammatory Markers in Consecutive Patients with Metabolic Syndrome

Abstract

BackgroundObstructive Sleep Apnea (OSA) is tightly linked to some components of Metabolic Syndrome (MetS). However, most of the evidence evaluated individual components of the MetS or patients with a diagnosis of OSA that were referred for sleep studies due to sleep complaints. Therefore, it is not clear whether OSA exacerbates the metabolic abnormalities in a representative sample of patients with MetS.Methodology/Principal FindingsWe studied 152 consecutive patients (age 48±9 years, body mass index 32.3±3.4 Kg/m2) newly diagnosed with MetS (Adult Treatment Panel III). All participants underwent standard polysomnography irrespective of sleep complaints, and laboratory measurements (glucose, lipid profile, uric acid and C-reactive protein). The prevalence of OSA (apnea-hypopnea index ≥15 events per hour of sleep) was 60.5%. Patients with OSA exhibited significantly higher levels of blood pressure, glucose, triglycerides, cholesterol, LDL, cholesterol/HDL ratio, triglycerides/HDL ratio, uric acid and C-reactive protein than patients without OSA. OSA was independently associated with 2 MetS criteria: triglycerides: OR: 3.26 (1.47–7.21) and glucose: OR: 2.31 (1.12–4.80). OSA was also independently associated with increased cholesterol/HDL ratio: OR: 2.38 (1.08–5.24), uric acid: OR: 4.19 (1.70–10.35) and C-reactive protein: OR: 6.10 (2.64–14.11). Indices of sleep apnea severity, apnea-hypopnea index and minimum oxygen saturation, were independently associated with increased levels of triglycerides, glucose as well as cholesterol/HDL ratio, uric acid and C-reactive protein. Excessive daytime sleepiness had no effect on the metabolic and inflammatory parameters.Conclusions/SignificanceUnrecognized OSA is common in consecutive patients with MetS. OSA may contribute to metabolic dysregulation and systemic inflammation in patients with MetS, regardless of symptoms of daytime sleepiness.

Sleep apnoea and metabolic dysfunction

“…The number of MetS criteria is defined as the metabolic index and can be used as an indicator of severity of metabolic abnormalities. Patients with severe OSA showed a significantly higher metabolic index compared to patients with mild-to-moderate OSA [45], and this finding has been also confirmed in patients primarily identified for the presence of MetS [46] or morbid obesity [47]. An independent role of OSA on metabolic abnormalities is not strongly supported by randomised controlled trials rigorously testing the effect of CPAP on metabolism in OSA patients.…”

Serum Inflammatory Markers in Obstructive Sleep Apnea: A Meta-Analysis

“…Yokoe et al, 26 Shamsuzzaman et al, 27 Bhushan et al, 53 Drager et al, 71 and Guven et al 72 have found OSAS to be a potential driver of elevated CRP levels independent of BMI. A number of others studies have not found this relation; instead, they found obesity, rather than sleep apnea or nocturnal hypoxemia, to be the key predictor of elevated CRP among OSA patients.…”

Microparticles and vascular dysfunction in obstructive sleep apnoea

“…OSA patients have elevated serum levels of TNF-a, interleukin (IL)-6, IL-8, C-reactive protein [76,77] and adhesion molecules (CD62L, soluble CD62E, CD62P, intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1) [77,78]. OSA is also associated with delayed neutrophil apoptosis and increased levels of adhesion molecules, which could contribute to enhanced neutrophil-leukocyte interactions, and facilitate free radical production and proteolytic release [79].…”