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Obstructive sleep apnoea (OSA) is considered as a risk factor for the development of arterial hypertension, coronary artery disease (CAD), myocardial infarction and stroke. These clinical manifestations are the consequences of elevated sympathetic activity, cardiovascular variability, intrathoracic pressure changes, inflammation, oxidative stress, endothelial dysfunction, insulin resistance and thrombosis provoked by OSA. As a result, OSA is often present in patients with cardiovascular disease (CVD) and the increased prevalence of CVD in OSA population raises both cardiovascular morbidity and mortality and the demand of healthcare resources. Observational cohort studies indicate that untreated patients with OSA have an increased risk of fatal and non-fatal cardiovascular events, an increased risk of sudden cardiac death during the sleeping hours and a higher risk of stroke or death from any cause. Continuous positive airway pressure (CPAP) and oral appliance therapy are the two treatments for OSA whose effects on cardiovascular endpoints have been assessed in randomised trials. There is increasing evidence that adequate CPAP therapy leads to a significant reduction in cardiovascular morbidity.

The European Sleep Apnoea Database (ESADA) reflects a network of 22 sleep disorder centres in Europe enabled by a COST action B26 programme. This ongoing project aims to describe differences in standard clinical care of patients with obstructive sleep apnoea (OSA) and to establish a resource for genetic research in this disorder. Patients with suspected OSA are consecutively included and followed up according to local clinical standards. Anthropometrics, medical history, medication, daytime symptoms and sleep data (polysomnography or cardiorespiratory polygraphy) are recorded in a structured web-based report form. 5,103 patients (1,426 females, mean±sd age 51.8±12.6 yrs, 79.4% with apnoea/hypopnoea index (AHI) ≥5 events·h(-1)) were included from March 15, 2007 to August 1, 2009. Morbid obesity (body mass index ≥35 kg·m(-2)) was present in 21.1% of males and 28.6% of females. Cardiovascular, metabolic and pulmonary comorbidities were frequent (49.1%, 32.9% and 14.2%, respectively). Patients investigated with a polygraphic method had a lower AHI than those undergoing polysomnography (23.2±23.5 versus 29.1±26.3 events·h(-1), p<0.0001). The ESADA is a rapidly growing multicentre patient cohort that enables unique outcome research opportunities and genotyping. The first cross-sectional analysis reveals a high prevalence of cardiovascular and metabolic morbidity in patients investigated for OSA.