Effects of obstructive sleep apnea with intermittent hypoxia on platelet aggregability.

Obstructive sleep apnea (OSA) is a risk factor for cardiovascular diseases. Platelets play key roles in the development of atherothrombosis. Several studies assessing platelet activation in patients with OSA have been published; however, there have been only a few studies with a small number of patients with OSA investigating platelet aggregability, which evaluates platelet aggregation more directly than the platelet activation status. We aimed to investigate the effects of OSA and nasal continuous positive airway pressure (nCPAP) therapy, a well-established treatment for OSA, on platelet aggregability.We examined 124 consecutive patients with snoring in whom the 3% oxygen desaturation index (3%ODI), a severity marker of OSA, and ADP- and collagen-induced platelet aggregability measured with the optical aggregometer were analyzed. ADP-induced platelet aggre-gability was increased more in patients with moderate-to-severe OSA (3%ODI>15) than in patients with non-to-mild OSA (p=0.029). In multiple linear models, 3%ODI significantly contributed to increased platelet aggregability induced by both ADP and collagen among 59 subjects with one or more risk factors for vascular diseases, such as smoking, hypertension, diabetes mellitus or hyperlipidemia. In 23 patients treated by nCPAP, collagen-induced platelet aggregability was ameliorated on Day 90, compared to at the baseline.The severity of OSA significantly contributed to platelet aggregability, which was improved by nCPAP treatment partially at three months.