Aspirin Resistance in OSA Patients
Condition: Obstructive Sleep Apnea
MeSH terms: Sleep Apnea Syndromes; Sleep Apnea, Obstructive
Study type: Observational

Summary: 
      Obstructive Sleep Apnea (OSA) patients are at increased risk of major cardiovascular events,
      so many patients take aspirin for prevention. Poor responsiveness to aspirin is a major
      clinical concern because it can potentially worsen the prognosis of OSA patients. However,
      continuous positive airway pressure (CPAP) therapy that is considered standard of care for
      OSA treatment may potentially lead to improvement in responsiveness to aspirin. This study
      will determine whether CPAP therapy decreases patients' aspirin resistance in OSA patients
      with a new diagnosis or existing moderate to severe OSA who are treated with CPAP and take
      aspirin for prevention.
    

Detailed description: 
      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.
    

Intervention name(s): Aspirin Resistance testing
Intervention type(s): Other
Intervention description(s): Aspirin resistance will be measured using platelet aggregometry (VerifyNow assay)
Intervention MeSH terms: Aspirin
Observational model: Other
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        Patients who come to the WCHN Pulmonary and Sleep Medicine Clinic either for a follow-up
        appointment to monitor their therapy for OSA or for an appointment to discuss a new
        diagnosis of OSA referred by their pulmonologist.