Aspirin Resistance in Obstructive Sleep Apnea Patients (ARISA Trial)

Obstructive Sleep Apnea (OSA) is a common sleep-related breathing disorder that afflicts more than 25 million adults in the United States. This number continues to rise yearly due to increased incidence of obesity in the United States. The prevalence of OSA among males and females is also on the rise with 34% of males and 17% of females diagnosed with this disease.

OSA is characterized as intermittent pharyngeal soft-tissue obstruction due to anatomical or positional etiology during sleep. This leads to episodes of hypoxemia and apneas which result in overall sleep fragmentation. The pathophysiology associated with OSA is complex. However, some proposed causes of OSA include hypoxia during sleep which causes increased circulating catecholamines and sympathetic activation, free radical formation leading to oxidative stress, increased cytokine release and endothelial dysfunction. These proposed mechanisms are also associated with increased platelet aggregation and hyperactivity and increase a patient's overall risk for cardiovascular morbidities.

Many patients with cardiovascular co-morbidities are taking aspirin for primary or secondary prevention. With a concomitant diagnosis of OSA, it is thought that these patients who are taking aspirin on a daily basis may become resistant to its effects based on how their OSA is controlled (ie. CPAP vs. Non-CPAP). Although aspirin resistance has been noted to be a "laboratory phenomenon," there have been studies which have shown a three-fold increase in cardiovascularco- morbidities in patients who were found to be aspirin resistant. In this study, it is our goal to determine the prevalence of aspirin resistance in patients who have a diagnosis of OSA and undergoing treatment with CPAP or Non-CPAP methods by measuring Aspirin Resistant Units (ARUs) using light aggregometry. It is our overall objective to determine whether or not OSA is an independent risk factor for aspirin resistance.

OSA patients are at increased risk of major cardiovascular events and aspirin resistance is associated with poor cardiovascular outcomes. Studying aspirin responsiveness in OSA patients may help to elucidate the potential role of platelet function testing, including the possible clinical implications of an aspirin therapy regimen guided by platelet function testing.