Prevalence and clinical correlates of white coat hypertension in chronic kidney disease

Abstract

The role of white coat hypertension (WCH) in the poor control of blood pressure (BP) in chronic kidney disease (CKD) is ill defined. We measured systolic clinical (CBP) and ambulatory blood pressure (ABP) in 290 consecutive patients with non-dialysis CKD [glomerular filtration rate (GFR) <60 ml/min/1.73 m(2)]. We defined normotension (NOR) if CBP and daytime ABP <130 mmHg, sustained hypertension (SH) when both BP >or=130 mmHg, WCH if only daytime ABP <130 mmHg, and masked hypertension (MH) when only CBP <130 mmHg. NOR patients were 15.5%, WCH 31.7%, SH 46.9% and MH 5.9%. Due to the high prevalence of WCH, achievement of BP target (<130 mmHg) was more than doubled by daytime ABP than CBP (47.2 vs 21.4%). WCH was characterized by prevalence of diabetes (31.5%), left ventricular hypertrophy (LVH; 50.0%) and CBP values (146 +/- 12 mmHg) lower than in SH (41.9%, 71.3% and 158 +/- 18 mmHg) but greater than in NOR (17.8%, 37.8% and 118 +/- 7 mmHg). Among patients with CBP >or=130 mmHg, the independent risk of having SH rather than WCH increased in the presence of higher CBP [Odds ration (OR) 1.61, 95% confidence intervals (CI) 1.29-2.02], LVH (OR 1.94, 95% CI 1.03-3.63) and proteinuria (OR 3.12, 95% CI 1.31-7.43). In the WCH group, 24 h, daytime and nighttime ABP were 118 +/- 7/68 +/- 8, 120 +/- 7/71 +/- 8 and 112 +/- 12/63 +/- 9 mmHg, respectively. In CKD, WCH is highly prevalent and can be predicted in the absence of higher CBP, LVH and proteinuria. In these patients, pursuing a low BP target may not be safe because of the risk of cardio-renal hypoperfusion especially at nighttime.