One Third of CKD Patients Have Masked Hypertension

Nearly one-third of patients with chronic kidney disease (CKD) with normal clinic blood pressure (BP) have masked hypertension (elevated ambulatory BP), which is associated with renal and cardiac damage, according to a new cross-sectional study.

The researchers performed 24-hour ambulatory BP in 1492 men and women with CKD enrolled in the Chronic Renal Insufficiency Cohort Study. They categorized participants into controlled BP, white-coat, masked, and sustained hypertension based on clinic and 24-hour ambulatory BP. The investigators obtained echocardiograms in 1278 of these subjects and measured pulse wave velocity (PWV) in 1394.
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The percent of participants with controlled BP, white-coat, masked, and sustained hypertension was 49.3%, 4.1%, 27.8%, and 18.8%, respectively. Compared to controlled BP, masked hypertension independently associated with low estimated glomerular filtration rate (eGFR) (-3.2 ml/min/1.73m2, 95% CI -5.5 to -0.9), higher proteinuria (+0.9 unit higher in log2 urine protein, 95% CI 0.7 to 1.1), and higher left ventricular mass index (+2.52 g/m2.7, CI 0.9 to 4.1) and PWV (+0.92 m/sec, CI 0.5 to 1.3).

Participants with masked hypertension had lower eGFR only in the presence of elevated nighttime BP (-3.6 ml/min/1.73m2, 95% CI -6.1 to -1.1 vs. -1.4 ml/min/1.73m2, 95% CI -6.9 to 4.0 among those with nighttime BP <120/70 mmHg; p-value for interaction with nighttime systolic BP 0.002).

“We need further research to determine whether treating masked hypertension is feasible and if so, whether doing so reduces the risk for adverse outcomes in a similar manner as seen in the hypertension trials conducted over the past 50 years—none of which included patients with masked hypertension because they have normal clinic BP,” said lead study author Paul Drawz, MD, MHS, MS, of the division of renal diseases and hypertension at the University of Minnesota.

To fill that research gap, he’s currently conducting a 4-month pilot study to determine whether treating patients with masked hypertension based on their ambulatory BP results safely modifies their BP pattern (i.e., reduces the prevalence of masked hypertension).

“If effective, we’ll conduct further preliminary studies of longer duration and eventually a randomized controlled trial with hard cardiovascular endpoints,” Drawz said.

—Mike Bederka

Reference:

Drawz PE, Alper AB, Anderson AH, et al. Masked hypertension and elevated nighttime blood pressure in CKD: prevalence and association with target organ damage. J Am Soc Nephrol. February 18, 2016 [epub ahead of print]. doi:10.2215/CJN.08530815.