Prognostic Significance of Ambulatory BP Monitoring in CKD: A Report from the Chronic Renal Insufficiency Cohort (CRIC) Study
Hypertension is an essential risk factor for morbidity and mortality in patients with CKD. There is less knowledge to suggest, whether Ambulatory BP Monitoring (ABPM) is of value in evaluating risk for outcomes in patients with CKD. The author Rahman and colleagues (2020) conducted a study published in “The Journal of American Society of Nephrology” under the title “Prognostic Significance of Ambulatory BP Monitoring in CKD: A Report from the Chronic Renal Insufficiency Cohort (CRIC) Study”. The summary of the findings is below:
Objective:
To investigate the association between BP profiles as per ABPM (White-coat effect, masked uncontrolled hypertension, and sustained hypertension) and cardiovascular outcomes and long-term kidney, and mortality in patients with CKD.
To examine the relation between 24-hour, day, and nighttime BPs; diurnal variation of BP; and clinical outcomes.
Method:
In the mean period of 6.72 years, the CRIC study investigated a total number of 1502 participants. Investigators evaluated ABPM, mean ambulatory BP monitoring and clinic BPs, and diurnal variation in BP such as reverse dipper, non-dipper, and dipper. The study outcome includes cardiovascular disease, kidney disease, and mortality.
Findings:
Subjects with masked uncontrolled hypertension (BP is lower in the clinic in comparison to out-of-clinic measurements) are at a high risk of cardiovascular disease and kidney disease. There was a stronger association between a higher risk of cardiovascular disease, kidney disease, and mortality with BP measures obtained using ABPM (24-hour mean, daytime, and nighttime BP) than clinic BP. Additionally, alterations of diurnal variation in BP (reverse-dipper and non-dipper profiles) were associated with an increased risk of progressive kidney disease, stroke, and peripheral arterial disease. Investigators highlight that participants with high BP both on the clinic and ambulatory BP (sustained hypertension) were at increased risk of clinical outcomes. When White-coat hypertension (BP in the clinic is higher than BP measured outside the clinic) is defined using the lower threshold of 130/80 mm Hg, it was associated with a higher risk of mortality. Additionally, white-coat hypertension participants with lower levels of GFR were associated with a higher risk of kidney outcome.
Hence, this study supports the broader use of ABPM to evaluate hypertension in patients with CKD.
Limitations:
The study findings are based on a single measurement of ABPM. Secondly, investigators weren’t able to compare home BP with ABPM as home BP monitoring was commonly used to evaluate out-of-clinic BP. It was an observational study of CRIC. Therefore, management of hypertension was under primary clinicians; hence, investigators cannot analyze the effect of hypertension treatment based on ABPM. Lastly, CRIC had a higher number of patients who were treated and controlled; it is unclear if similar results will be observed in less well-treated populations.
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