Serum cardiovascular risk factors in obstructive sleep apnea

Obstructive sleep apnea (OSA) patients have increased cardiovascular morbidity and mortality. The cardiovascular markers associated with OSA are currently not defined.

The aims of this study were to determine whether OSA is associated with serum cardiac risk markers and to investigate the relationship between them.

Sixty-two male patients were classified into two groups with respect to apnea-hypopnea index (AHI): group 1, sleep apnea (n = 30), with AHI > 5; and group 2 (n = 32), with AHI < 5. We compared cardiovascular risk factors in both groups with control subjects (n = 30) without OSA (AHI < 1). Serum cholesterol, triglyceride, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein A-I, apolipoprotein B, lipoprotein (a), C-reactive protein (CRP), and homocysteine were measured. Statistical significance was assessed with analysis of variance at p < 0.05. In correlation analysis, Pearson correlation was used.

There was no significant difference between group 1 and group 2 in total cholesterol, LDL-C, HDL-C, triglyceride, apolipoprotein A-I, apolipoprotein B, and lipoprotein (a). All of the M-mode echocardiographic parameters were in the normal reference range. Serum homocysteine and CRP levels were significantly increased in group 1 compared to group 2 (p < 0.05). Serum CRP values were increased in both group 1 and group 2 when compared with control subjects (p < 0.05). Serum homocysteine values were higher in group 1 than in control subjects (p < 0.05).

Our results show that OSA syndrome is associated not only with slight hyperhomocysteinemia but also with increased CRP concentrations. Increased plasma concentrations of homocysteine and CRP can be useful in clinical practice to be predictor of long-term prognosis for cardiovascular disease and the treatment of OSA.