[Obstructive sleep apnea and risk factors for coronary artery disease]

Obstructive sleep apnoea (OSA) is strongly associated with obesity, especially abdominal obesity. Obesity in turn is a well-known risk factor for coronary artery disease (CAD). The aim of our study was to evaluate the relationship between OSA severity and CAD risk factors.

The sample consisted of 73 subjects (mean age +/- SE, 46.7 +/- 1 years) referred to a sleep laboratory. Subjects were either: 1. obese with OSA (O-OSA group n = 35; body mass index, BMI ł 30 kg/m2; apnoea/hypopnoea index, AHI > 35), 2. non-obese with OSA (BO-OSA group n = 14; BMI < 27 kg/m2; AHI > 35), or 3. obese without OSA (O-Z group n = 24; BMI ł 30 kg/m2; AHI < 5). All subjects underwent full overnight polysomnography. Blood samples were taken from all subject, for fasting levels of insulin (INS), glucose (GLU), total, HDL and LDL cholesterol, triglyceride (TG) and uric acid (UA).

O-OSA had significantly higher INS and UA levels (p < 0.05) compared to BO-OSA and O-Z. GLU and lipid levels were comparable in the studied groups. GLU level correlated (p < 0.05) negatively to minimum oxyhemoglobin saturation (SAT-MIN) and positively to neck circumference. TG and UA levels were correlated (p < 0.05) positively to AHI and negatively to SAT-MIN. UA level was also positively correlated (p < 0.05) to BMI, waist/hip circumference ratio (WHR), and INS level. INS level correlated (p < 0.05) positively to AHI, T90, WHR and UA, and negatively to SAT-MIN and mean oxyhemoglobin saturation. After adjusting for the influence of OSA and obesity (multiple regression analysis), we found independent negative correlations (p < 0.05) between: GLU level and SAT-MIN, UA level and SAT-MIN, and INS level and SAT-MIN. An independent, positive correlation (p < 0.05) was found between TG level and AHI.

Results of our study suggest that OSA increases the risk of coronary artery disease by increasing plasma levels of glucose, triglyceride and insulin, independent of obesity.