Does CPAP treatment in mild obstructive sleep apnea affect blood pressure?

Objectives: Obstructive sleep apnea (OSA) is associated with significant cardiovascular (CV) morbidity. Continuous positive airway pressure (CPAP) is the standard treatment for moderate to severe OSA, resulting in a reduction in CV morbidity. No studies have compared CV outcomes between CPAP and no CPAP in mild OSA (5 >= AHI < 15). Methods: Retrospective cohort study of subjects (age >= 18) with mild OSA diagnosed between 2004 and 2006. Subjects with a history of hypertension, angina, stroke and smoking were excluded. Subjects were stratified into two groups: CPAP (n = 93) or no CPAP (n = 162). The mean blood pressures (MBP) were compared 2 years after the diagnosis of OSA was established. Results: Unmatched for covariates (age, sex, BMI, neck circumference, AHI, arousal index and family h/o CV disorders), subjects with mild OSA on CPAP had a 1.97 point reduction, and no CPAP resulted in a 9.61 point elevation (p < 0.0001) in MBP. With propensity score matching for covariates, the mean difference in MBP was -1.97 (95% CI: -14.03, -9.92: p < 0.0001) with a sensitivity analysis of 2.646. Conclusion: This study shows an elevation of the MBP in mild OSA patients who were not treated with CPAP. CPAP treatment in mild OSA patients decreased the MBP over a 2-year period. (C) 2010 Elsevier B.V. All rights reserved.