Opponent's comments.

Out-of-hemodialysis-unit blood pressure is a superior determinant of left ventricular hypertrophy. Home blood pressures are of greater prog-nostic value than hemodialysis unit recordings. Home blood pressure monitoring in blood pressure control among haemodialysis patients: an open rando-mized clinical trial. et al. Blood pressure and risk of all-cause mortality in advanced chronic kidney disease and hemodialysis: the chronic renal insufficiency cohort study. Nocturnal hypoxemia, night-day arterial pressure changes and left ventricular geometry in dialysis patients. Nocturnal blood pressure and 24-hour pulse pressure are potent indicators of mortality in hemodialysis patients. Prognostic value of isolated nocturnal hyperten-sion on ambulatory measurement in 8711 individuals from 10 populations. Relative effectiveness of clinic and home blood pressure monitoring compared with ambulatory blood pressure monitoring in diagnosis of hypertension: systematic review. BMJ 2011; 342: d3621 36. Kelley K, Light RP, Agarwal R. Trended cosinor change model for analyzing hemodynamic rhythm patterns in hemodialysis patients. A quantitative analysis of the effects of activity and time of day on the diurnal variations of blood pressure. Dr Agarwal presents a passionate argument for the use of ambulatory blood pressure monitoring (ABPM), but fails to address the added value of this measurement, or the practical use of ABPM beyond research studies and trials. ABPM provides more information on BP than home monitoring, single clinic readings or even the 'before and after' readings that we routinely collect on dialysis. The additional detail that ABPM and, to a lesser extent, home readings provide clearer associations between blood pressure parameters and outcomes in the dialysis population. This reflects the repeated measurements and is a strength of ABPM in epidemiological studies and clinical trials [1]. However, it does not necessarily help in the management of individual patients. Dr Agarwal argues that the pattern of change in interdialytic BP demonstrated by ABPM identifies patients with large fluid gains. While I—and I suspect everyone else—would agree that this is a major problem, with proven links to adverse outcomes [2], I suspect that no one would advocate the use of ABPM to direct fluid management— preferring anything from weight and clinical assessment to lung ultrasound and echocardiography. One of the issues about focussing on a single technique or measurement is that it detracts from the bigger picture. Dr Agarwal argues that failure of the AURORA trial to identify