1017 CLINICAL OUTCOMES OF CONTINUOUS POSITIVE AIRWAY PRESSURE IN PATIENTS WITH OBSTRUCTIVE SLEEP APNEA AND NON-DIPPING BLOOD PRESSURE: A PROSPECTIVE COHORT STUDY

Abstract

Introduction: Nondipping blood pressure (BP) and obstructive sleep apnea (OSA) both carry an increased risk of cardiovascular events and mortality. We aim to investigate the effects of 6 months of continuous positive airway pressure (CPAP) treatment on blood pressure (BP) and urine albumin/creatinine ratio (ACR) in OSA patients with nondipping patterns. Method(s): We prospectively enrolled adult patients with severe OSA (AHI>30) from November 2010 to December 2015 for ambulatory 24-hr BP study. Baseline 24hr BP was recorded, urine was collected for ACR and peripheral venous blood samples were collected for the analysis of CBC-DC, creatinine, lipid profile, and high sensitivity CRP (hsCRP). After CPAP use, we measured 24-hr BP, hsCRP and ACR at 3 and 6 months separately. Statistical analyses (paired T test, generalized estimating equation) were performed by SAS. Result(s): A total of 77 patients were enrolled. At baseline, 42(54.5%) of patients were dippers and 35(45.5%) were non-dippers (a decrease of less than 10% in the average nighttime blood pressure compared with the average daytime blood pressure). In non-dippers, the mean AHI was 70.0 (SD, 22.7), baseline 24-hr mean BP was 125.0(SD, 17.1) mmHg (systolic blood pressure (SBP): 140.1(SD, 19.7) mmHg, diastolic blood pressure (DBP): 95.0(SD, 13.8)mmHg). CPAP treatment decreased SBP by 1.59 mmHg (95% confidence interval (CI):-9.2 to 3.6; p=0.287), and diastolic blood pressure by 3.13 mmHg (95%CI:-7.5 to 0.7; p=0.062). After 6 months of CPAP treatment, 20(57.1%) of non-dippers displayed dipping BP pattern and 15(42.9%) were refractory non-dippers (average day-night BP decrease 14.3 +/- 3.6%, 3.0 +/- 5.1%; P<0.001). Non-dippers had a reduction in ACR (-14.0 +/- 42.7 mg/L) (p=0.061) and those who displayed dipping pattern after CPAP had the most significant reduction in ACR (-7.0 +/- 10.25 mg/L) (p=0.010). HsCRP level decreased significantly in non-dippers who had dipping pattern after CPAP (-1.13 +/- 3.73 mg/L) when compared with refractory non-dippers (3.05 +/- 6.08 mg/L) (p=0.024). Conclusion(s): In severe OSA patients with nondipping BP, CPAP treatment for 6 months improved BP pattern. In those who displayed dipper pattern after CPAP, the decrease of ACR was significant. This effect of non-dippers converting to dippers was associated with greater decrease in hsCRP.