Ambulatory BP Data Predict Renal and Cardiovascular Risks in Chronic Kidney Disease

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In patients with chronic kidney disease (CKD) not yet receiving dialysis, ambulatory BP monitoring improves the ability to predict renal and cardiovascular events, according to a study published in the Archives of Internal Medicine.
The Italian multicenter cohort study included 436 patients with stage 2–5 CKD who were not receiving dialysis. At baseline, the GFR was 42.9 mL/min per 1.73 m2; diabetes was present in 36.5 percent of patients and cardiovascular disease in 30.5 percent. Office and ambulatory BP data were compared for their ability to predict time to renal death (ESRD or death) and time to fatal and nonfatal cardiovascular events. The median follow-up time was 4.2 years.
The mean office BP was 146/82 mm Hg. During ambulatory monitoring, the daytime BP was 131/75 mmHg and the nighttime BP 122/66 mmHg. At follow-up, 155 patients had reached the renal endpoint, and 103 had reached the cardiovascular endpoint.
Patients with daytime systolic BP greater than 126 to 135 mmHg had a higher rate of cardiovascular events: adjusted hazard ratios (HR) of 2.23 at a level of 136–146 mmHg and 3.07 at higher than 146 mmHg. The same groups were at increased risk of renal death: HR 1.72 and 1.85, respectively.
Patients with nighttime systolic BP greater than 106–114 mmHg were at increased risk of the cardiovascular endpoint: HR 2.52 at 125–137 mmHg and 4.00 at greater than 137 mmHg. They were also at increased risk of renal death: HR 1.87 and 2.54, respectively. The rates of both outcomes were higher in patients who were “nondippers” and “reverse dippers” receiving ambulatory BP monitoring. Office BP measurements did not predict either outcome.
Ambulatory BP monitoring provides additional prognostic value in patients with essential hypertension. The new study suggests that ambulatory BP measurement—especially nighttime BP data—allows more accurate assessment of adverse renal and cardiovascular outcomes in patients with CKD who are not receiving dialysis. By contrast, office BP measurements provide little or no useful information about these risks [Minutolo R, et al. Prognostic role of ambulatory blood pressure measurement in patients with nondialysis chronic kidney disease. Arch Intern Med 2011; 171;1090–1098].
September 2011 (Vol. 3, Number 9)