Prognostic Significance of Ambulatory BP Monitoring in CKD: A Report from the Chronic Renal Insufficiency Cohort (CRIC) Study
Authors: Rahman Mahboob , Wang Xue , Bundy Joshua D. , Charleston Jeanne , Cohen Debbie , Cohen Jordana , Drawz Paul E. , Ghazi Lama , Horowitz Edward , Lash James P. , Schrauben Sarah , Weir Matthew R. , Xie Dawei , Townsend Raymond R. ,   the CRIC Study Investigators
Published: September 2020

Significance Statement
Although there is increasing emphasis on out-of-office BP measurement, few studies have evaluated the prognostic significance of ambulatory BP monitoring in patients with CKD. In this cohort of 1502 participants with CKD, BP metrics derived from ambulatory BP (masked hypertension, 24-hour and nighttime BP, and reverse dipper [higher nighttime BP] diurnal profile) were strongly and independently associated with clinical outcomes. For example, presence of masked uncontrolled hypertension and higher mean 24-hour BP were independently associated with high risk of cardiovascular disease and kidney disease progression, and participants with reverse dipper BP were at high risk of kidney disease progression, stroke, and peripheral artery disease compared with those who experienced a nighttime dip in BP. These data support the broader use of ambulatory BP monitoring for evaluation of hypertension in patients with CKD.

Background
Whether ambulatory BP monitoring is of value in evaluating risk for outcomes in patients with CKD is not clear.

Methods
We followed 1502 participants of the Chronic Renal Insufficiency Cohort (CRIC) Study for a mean of 6.72 years. We evaluated, as exposures, ambulatory BP monitoring profiles (masked uncontrolled hypertension, white-coat effect, sustained hypertension, and controlled BP), mean ambulatory BP monitoring and clinic BPs, and diurnal variation in BP—reverse dipper (higher at nighttime), nondipper, and dipper (lower at nighttime). Outcomes included cardiovascular disease (a composite of myocardial infarction, cerebrovascular accident, heart failure, and peripheral arterial disease), kidney disease (a composite of ESKD or halving of the eGFR), and mortality.

Results
Compared with having controlled BP, the presence of masked uncontrolled hypertension independently associated with higher risk of the cardiovascular outcome and the kidney outcome, but not with all-cause mortality. Higher mean 24-hour systolic BP associated with higher risk of cardiovascular outcome, kidney outcome, and mortality, independent of clinic BP. Participants with the reverse-dipper profile of diurnal BP variation were at higher risk of the kidney outcome.

Conclusions
In this cohort of participants with CKD, BP metrics derived from ambulatory BP monitoring are associated with cardiovascular outcomes, kidney outcomes, and mortality, independent of clinic BP. Masked uncontrolled hypertension and mean 24-hour BP associated with high risk of cardiovascular disease and progression of kidney disease. Alterations of diurnal variation in BP are associated with high risk of progression of kidney disease, stroke, and peripheral arterial disease. These data support the wider use of ambulatory BP monitoring in the evaluation of hypertension in patients with CKD.

Podcast
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