Effectiveness of Nasal Continuous Positive Airway Pressure (CPAP) Therapy on Cardiovascular Outcomes in Obstructive Sleep Apnea-Hypopnea Syndrome (OSAHS)

Abstract

Background: There are ethical issues about randomizing individuals with obstructive sleep apnea-hypopnea syndrome (OSAHS) into groups that receive therapy and those that do not, which means that longitudinal studies are necessary. Objective: To evaluate the effectiveness of nasal continuous positive airway pressure (CPAP) therapy on cardiovascular outcomes in OSAHS patients and to discuss the use of OSAHS treatment. Design: A prospective, patient-based study using retrospective observational data was performed. Cox multivariate regression analysis was performed to determine the adjusted effect of CPAP-treatment on survival in cardiovascular events (CVE). Setting: Sleep Unit of Burgos, Spain. Patients: All 887 patients (791 men) with OSAHS were diagnosed by Polysomnography in the Sleep Unit, between 1997 and 2002. Intervention: CPAP-treatment versus non CPAP-treatment, according to Spanish Society of Pulmonary and Thoracic Surgery (SEPAR) criteria. Measurements: The cardiovascular disease data were obtained from hospital records. Results: The average follow-up period was 4.1 years. CPAP-treatment patients had a higher mean apnea-hypopnea index score than the untreated group (45.9 [Standard Deviation (SD): 28.2] versus 25.3 (SD: 17.8), respectively; P < 0.001), as well as a higher Body Mass Index, Epworth and Arousals, but age and sex were similar in both groups. Cardiovascular disease was more common in the untreated group than in the CPAP-treated group during follow-up (3.0 versus 1.99 cardiovascular events/100 persons-years, respectively; P=0.1547). Upon multivariate analysis, age, sex, prior cardiovascular disease, diabetes mellitus and CPAP (hazard ratio= 0.519, 95% confidence interval: 0.288-0.935) remained as statistically significant predictors of survival in cardiovascular events. The mortality rate was greater in women than men. Conclusions: The data support a protective effect of CPAP therapy against cardiovascular disease in patients with OSAHS and different cardiovascular morbidity and mortality by gender. CPAP therapy shows a positive benefit/risk balance.