title: Chronobiology of arterial hypertension in hemodialysis patients: implications for home blood pressure monitoring.
abstract: BACKGROUND
  Hemodialysis patients have a steady increase in blood pressure (BP) during the 44-hour interdialytic interval when ambulatory BP monitoring is used. Home BP recording allows for a longer period of monitoring between dialysis treatments and may better define the chronobiological characteristics of arterial hypertension. This study sought to determine the optimal time to perform home BP monitoring in hemodialysis patients to improve the strength of prediction of 44-hour interdialytic ambulatory BP.
  
  
  METHODS
  Diagnostic test study.
  
  
  METHODS
  This is an ancillary analysis of patients participating in the Dry-weight Reduction in Hypertensive Hemodialysis Patients (DRIP) trial.
  
  
  METHODS
  Home BP measured 3 times daily for 1 week by using a validated oscillometric monitor on 3 occasions at 4-week intervals after randomization. Home BP measured during the first third, second third, and last third of time elapsed after the dialysis treatment, as well as each third of the dialysis treatment, was compared with the overall ambulatory BP.
  
  
  METHODS
  Interdialytic ambulatory BP measured on 3 occasions at 4-week intervals after randomization.
  
  
  RESULTS
  During the interdialytic interval, we found an increase in systolic ambulatory BP of 0.30 +/- 0.36 mm Hg/h and an increase in systolic home BP of 0.40 +/- 0.25 mm Hg/h. This relationship in home BP reached a plateau after approximately 48 hours. A similar pattern was seen for diastolic home BP. Probing dry weight steepened the slope of ambulatory BP, but did not alter the time-dependent relationship of home BP. Home BP was on average higher (bias) by 14.1 (95% confidence interval, 12.0 to 16.2)/5.7 mm Hg (95% confidence interval, 4.6 to 6.9). The SD of differences between methods (precision) was 4.6/2.8 mm Hg. Measurement of BP during each third of the interdialytic interval gave the best precision, measured by using model fit compared with ambulatory BP measurements.
  
  
  CONCLUSIONS
  Our cohort was overrepresented by African American hemodialysis patients. Whether African American participants have a different pattern of BP response than non-African American participants in the interdialytic period is not known.
  
  
  CONCLUSIONS
  Our findings suggest that time elapsed after a dialysis treatment must be considered in interpreting home BP recordings in hemodialysis patients. Home BP measured in each third of the interdialytic interval is likely to yield the most reliable BP estimate.
authors.affiliation: Division of Nephrology, Richard L. Roudebush VA Medical Center, Indianapolis, IN, USA. ragarwal@iupui.edu
authors.forename: Rajiv
authors.initials: R
authors.lastname: Agarwal
authors.forename: Robert P
authors.initials: RP
authors.lastname: Light
mesh_terms: D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data; D000368:Aged; D000959:Antihypertensive Agents / Q000627:therapeutic use; D001794:Blood Pressure; D018660:Blood Pressure Monitoring, Ambulatory; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D006973:Hypertension / Q000208:ethnology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D016032:Randomized Controlled Trials as Topic; D006435:Renal Dialysis
chemical_list: D000959:Antihypertensive Agents