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; eGFRX60 ml min À1 per 1.73 m 2 ) or the low (L; eGFRo60 ml min À1 per 1.73 m 2 ) group. The patients in the L group were significantly older than those in the H group (Po0.001), and body mass index was significantly smaller in the L group than in the H group (P¼0.025). The rate of patients treated with statin (P¼0.030) and the levels of both triglyceride (P¼0.006) and creatinine (Po0.001) 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, P¼0.033; and 76.1±9.5 mm Hg, P¼0.012, 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. Keywords: ambulatory blood pressure monitoring; circadian blood pressure; estimated glomerular filtration rate; nocturnal hypertension; polysomnography
INTRODUCTIONIt is important to consider blood pressure (BP) outside of a clinic setting when treating patients with hypertension, because BP measurements obtained in a clinic setting are not representative of BP outside of the clinic setting. Abnormal changes in circadian BP are considered to increase the risk of cardiovascular event. Patients with nocturnal hypertension or a morning BP surge tend to have a higher incidence of silent cerebrovascular disease 1 and greater intima-media and relative wall thickness compared with normotensive patients. 2 Nocturnal hypertension and morning BP surge are induced by sleep disordered breathing, which can be observed in 22% of Japanese adult males. 3 Typical clinical features of BP changes in patients with sleep disordered breathing and those with sleep apnea syndrome (SAS) are nocturnal hypertension and non-dipper patterns of circadian BP. As the severity of SAS increases, sleep BP is elevated even in a patient whose BP is within the normal range in the clinic. Moreover, the incidence of nocturnal cardiovascular events while sleeping increases in these patients. [4][5][6] Chronic kidney disease (CKD) seems to be tightly linked with nocturnal hypertension and morning BP surge. 7 CKD poses a high risk for the onset of cardiovascu...