Is Mean Platelet Volume Really a Severity Marker for Obstructive Sleep Apnea Syndrome without Comorbidities?

Obstructive sleep apnea syndrome (OSAS) is a common disorder that can lead to significant cardiovascular complications. Several studies have reported increased platelet activation and aggregation in patients with OSAS. In this study we aimed to show a correlation between mean platelet volume (MPV) and severity of OSAS in patients with OSAS without any overt cardiac disease or diabetes. The polysomnography recordings of 556 consecutive patients admitted to the sleep laboratory between January 2012 and July 2012 were retrospectively evaluated. The relationship between polysomnographic parameters and biochemical parameters was assessed. Polysomnographic results of 200 patients (154 males [77%]; mean age, 44.5？±？11.4 years) were included. No correlation was observed between MPV and the average oxygen saturation index, the minimum desaturation index, or the oxygen desaturation index in the study population as well as in severe OSAS group (AHI？>？30). The only correlation was found between MPV and AHI in the severe OSAS group . MPV was not correlated with OSAS severity in patients without any overt cardiac disease or diabetes. These findings raise doubts about the suggestion that MPV might be a marker for OSAS severity, as recommended in earlier studies. Thus, further prospective data are needed. 1. Introduction Obstructive sleep apnea (OSA) is characterized by recurrent episodes of partial or complete upper airway obstruction during sleep. It occurs as combined episodes of apnea and hypopnea that cause sleep fragmentation or excessive daytime sleepiness. It is a common disorder affecting 2% and 4% of middle aged women and men, respectively [1]. The severity of OSAS is estimated by the number of apnea-hypopnea episodes per hour of sleep and is expressed as the apnea-hypopnea index (AHI) [2]. Although the underlying mechanisms and etiologies are not completely understood, OSAS can lead to significant cardiovascular complications [3], including heart failure, acute myocardial infarction, arrhythmias, hypertension, pulmonary hypertension, and stroke [4]. Increased platelet activation and aggregation are closely related to cardiovascular complications [5]. Several studies have reported increased platelet activation and aggregation in patients with OSAS [6, 7]. It has been shown that platelet size, measured by mean platelet volume (MPV), correlates with platelet reactivity and is an easy and useful tool for indirect monitoring of platelet activity. Larger platelets have higher thrombotic potential [8]. MPV plays an important role in the pathophysiology of