White-Coat and Masked Hypertension in Hemodialysis Patients

Objective: Unlike the general population or patients with earlier stages of chronic kidney disease, there are no clear diagnostic criteria for white-coat and masked hypertension in the hemodialysis population. In the present study, we aimed to estimate the prevalence of these 2 BP phenotypes using routine predialysis BP recordings in combination with 44-hour ambulatory BP monitoring (ABPM). Design and method: In a cohort of 70 hemodialysis patients, hypertension was assessed with 2 methods: (i) the average of routine predialysis BP recordings over 6 consecuitive dialysis sessions; (ii) ABPM over an entire 44-hour interdialytic period (BP measurements at 20-minute intervals; Microlife WatchBP O3 device). The thresholds of 140/90 mmHg and 130/80 mmHg were used to define abnormal predialysis and ambulatory BP, respectively. Results: Study participants (45 males and 25 females) had a mean age of 65.3±13.3 years and a median dialysis vintage of 15 months. The prevalence of hypertension was 88.6% by predialysis BP recordings and 90% by ABPM. In all, 61 patients were being treated with an average of 1.5±0.6 antihypertensive medications daily. In all, 51.4% of patients had either normotension or adequately controlled hypertension confirmed by the 2 different BP monitoring techniques, whereas 18.6% of patients had uncontrolled hypertension confirmed by both techniques. The prevalence of white-coat hypertension was 24.3% and the prevalence of masked hypertension was 5.7%. A 2-week averaged routine predialysis BP at the threshold of 140/90 mmHg provided 77.8% sensitivity and 30.8% specificity for the diagnosis of an average 44-hour ambulatory BPequal or higher than 130/80 mmHg. The agreement between these 2 techniques for the identification of patients with adequately controlled hypertension was poor (k-statistic: 0.378, P<0.001). Conclusions: This study shows that in approximately 30% of hemodialysis patients, there is lack of concordance between routine predialysis BP recordings and ABPM for the determination of BP control status. Routine predialysis BP recordings, even when averaged over 6 consecutive dialysis sessions, are inaccurate estimates of the actual BP load, as assessed by ABPM.