Prognosis and cardiovascular morbidity and mortality in prospective study of hypertensive patients with obstructive sleep apnea syndrome in St Petersburg, Russia

BACKGROUND: To assess the impact of obstructive sleep apnea-hypopnea syndrome (OSAHS) on prognosis and cardiovascular morbidity and mortality in relation to other major cardiovascular risk factors. MATERIAL/METHODS: This prospective study recruited 234 patients from an out-patient clinic. Based on the Berlin questionnaire, 147 patients (90 males, mean age 52.1±10.4 years) with highly suspected sleep breathing disorders were included in the study. Based on cardiorespiratory monitoring, patients were divided into 2 groups: 42 patients without sleep breathing disorders (SBD), and 105 patients with OSAHS. Among these, 12 patients started CPAP therapy and formed the third group. RESULTS: The mean follow-up period was 46.4±14.3 months. Event-free survival was lowest in the untreated OSAHS patients (log rank test 6.732, p=0.035). In the non-adjusted regression model, OSAHS was also associated with a higher risk of cardiovascular events (OR=8.557, 95% CI 1.142–64.131, p=0.037). OSAHS patients demonstrated higher rates of hospitalization compared to the control group without SBD (OR 2.750, 95%CI 1.100–6.873, p=0.04). CONCLUSIONS: OSAHS hypertensive patients, and in particular, according to our model, patients with severe OSAHS (AHI ≥30/h), are at higher risk of fatal and non-fatal cardiovascular events. Moreover, untreated OSAHS patients demonstrate higher rates of hospitalization caused by the onset or deterioration of cardiovascular disease.