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08-01-2012 | Cardiology | Article

Six-monthly repeat BP measurement ideal in white-coat resistant hypertension

Abstract

Free abstract

MedWire News: Researchers say the appropriate time interval to repeat ambulatory blood pressure monitoring (ABPM) in patients with white-coat resistant hypertension (RH) is at 3 months after the first diagnosis and every 6 months to 1 year thereafter.

However, repeating ABPM periodically is costly and uncomfortable for patients, resulting in low cost-effectiveness and low acceptance, report Elizabeth Muxfeldt (Federal University of Rio de Janeiro, Brazil) and co-authors in the journal Hypertension.

Therefore, future studies should evaluate other methods of out-of-office BP assessment in patients with RH, such as home BP monitoring, they add.

Muxfeldt et al explain that resistant hypertension (defined as uncontrolled BP despite use of optimal regimen with ≥3 antihypertensive drugs, ideally using a diuretic) is classified by ABPM into true (uncontrolled) RH (office BP ≥140/90 mmHg and 24-hour BP ≥130/80 mmHg) and white-coat (controlled) RH (office BP ≥140/90 mmHg and 24-hour BP <130/80 mmHg).

However, patients are found to switch between these categories without their office BP changing, necessitating repeat periodic ABPM assessments, Muxfeldt and team say. The researchers sought to investigate how frequently these repeat measurements should be done.

The study involved 198 patients with white-coat RH on ABPM. All patients underwent a second confirmatory examination 3 months later. Patients who were diagnosed with white-coat RH (n=144) then underwent two repeat BP measurements at intervals of 6 months. All patients used the same antihypertensive therapeutic regimen throughout the study.

At the third and fourth ABPMs, 74% and 79% of patients sustained their white-coat RH diagnosis, respectively. Patients who sustained their white-coat RH diagnosis on the fourth ABPM had significantly lower office and ambulatory systolic BPs on the confirmatory (second) ABPM than those with true RH.

Multivariate analysis revealed that a daytime systolic BP of 115 mmHg or lower on the confirmatory ABPM was the best predictor of white-coat RH status persistence. Indeed, its presence tripled the chance of white-coat RH persistence after 1 year (p=0.007).

"Based on these results we proposed an algorithm to guide the follow-up of white-coat RH patients," write the authors.

They suggest that after a confirmatory ABPM at 3 months, the procedure should be repeated at 6-month intervals, except in patients with a daytime systolic BP of 115 mmHg or lower, who can repeat it annually.

Commenting on future directions for research, they say: "Serial changes in office and ambulatory BPs during follow-up of RH patients should be addressed… to evaluate whether this tight BP control in [white-coat] RH patients would translate into better cardiovascular outcomes."

MedWire (http://www.medwire-news.md/) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2012

By Piriya Mahendra

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