Relationship between chronic kidney disease and sleep blood pressure in patients with sleep apnea syndrome

Chronic kidney disease (CKD) is common disease in patients with sleep apnea syndrome (SAS), which is considered to be responsible for secondary and nocturnal hypertension. In this study, we assessed blood pressure (BP) changes in SAS patients with CKD. Of 460 Japanese outpatients with suspected SAS who underwent ambulatory BP monitoring within 3 months of overnight polysomnography, 198 patients (172 males and 26 females) who were not receiving treatment with antihypertensives or nitroglycerin were enrolled. The estimated glomerular filtration rate (eGFR) was calculated, and the patients were stratified into the high (H; eGFR >= 60 ml min(-1) per 1.73 m(2)) or the low (L; eGFR<60 ml min(-1) per 1.73 m(2)) group. The patients in the L group were significantly older than those in the H group (P<0.001), and body mass index was significantly smaller in the L group than in the H group (P=0.025). The rate of patients treated with statin (P=0.030) and the levels of both triglyceride (P=0.006) and creatinine (P<0.001) differed significantly between the two groups. The sleep data, 24-h BP, awake BP and morning BP showed no significant differences between the two groups. However, sleep systolic and diastolic BPs were significantly higher in the L group (122.5 +/- 16.7 mm Hg and 81.1 +/- 12.2 mm Hg, respectively) than in the H group (117.1 +/- 11.8 mm Hg, P=0.033; and 76.1 +/- 9.5 mm Hg, P=0.012, respectively). SAS patients with CKD had elevated sleep BP. This result suggests that appropriate treatments for both SAS and CKD prevent sleep BP elevation, which is considered a risk factor for the onset risk of a cardiovascular event. Hypertension Research (2010) 33, 1278-1282; doi: 10.1038/hr.2010.197; published online 21 October 2010