Research Article
Refractory and resistant hypertension: characteristics and differences observed in a specialized clinic

https://doi.org/10.1016/j.jash.2015.03.005Get rights and content

Highlights

  • We assessed a cohort of RHTN patients for differences in resistant and refractory

  • Resistant and refractory hypertensives present notable phenotypical differences

  • The white–coat effect prevails in refractory hypertension

  • Left ventricular hypertrophy and black race are strongly linked to refractory HTN

Abstract

Resistant hypertension (RH) is defined as uncontrolled blood pressure (BP) despite the use of ≥3 anti–hypertensive drugs, or controlled requiring use of ≥4 drugs. Recently, a new definition for an extreme phenotype of RH (uncontrolled BP using at least five drugs) has emerged—the refractory hypertension (RfH). Although characteristics of RH are well established, little is known about this newly described subgroup. For this work, 116 subjects with RH were enrolled from a specialized clinic and divided into RH (n = 80) and RfH (n = 36). Subjects were submitted to echocardiography, 24–hour ambulatory BP measurement and biochemical analyses. Logistic regression analysis demonstrated that: (1) white–coat effect (odds ratio [OR], 3.23; 95% confidence interval [CI], 1.12–9.27; P = .03), (2) black race (OR, 6.67; 95% CI, 1.99–16.16; P < .001), and (3) left ventricular mass index (OR, 1.02; 95% CI, 1.01–1.03; P = .04) were independent predictors of refractoriness. In conclusion, RfH and RH present different patient characteristics, and these phenotypic aspects can be useful for better understanding this harder–to–treat subgroup.

Introduction

Resistant hypertension (RH) is a difficult–to–treat part of hypertension in which subjects require at least 4 drugs, ideally with a diuretic, to control their blood pressure (BP) levels, or use at least three drugs with no success in achieving BP control.1 Its prevalence vary from 8.9% to 14.5%.2, 3, 4 This condition poses greater cardiovascular risk and worst outcomes compared with controlled hypertensives.5 Although RH as a whole represents a group with adverse clinical and metabolic features, a part of them should have an even more unfavorable phenotype associated with the lack of BP control.

For this reason, recently, a new definition for an extreme phenotypic subgroup of RH has been proposed—the refractory hypertension (RfH). It consists in a part of resistant hypertensive patients who remain uncontrolled despite the use of five or more anti–hypertensive agents.6, 7 Although this subgroup should pertain specific characteristics, no data deriving from a specialized clinic with this definition have been reported.

We aimed to identify patients with RfH in a specialized RH clinic, characterizing their phenotype as well as the factors associated to treatment failure.

Section snippets

Study Population

For this cross–sectional study, we enrolled 116 individuals diagnosed with true RH according to international guidelines,1 from our Resistant Hypertension Clinic at the University of Campinas (Campinas, Brazil). The diagnosis of RH was given after at least 6 months of follow–up with patients precisely investigated for pseudoresistance (due to non–adherence, non–optimal doses of anti–hypertensive drugs, or white–coat hypertension)8, 9 and for the actual need of the prescribed medication.

Results

We found a 31% prevalence of RfH among all 116 patients previously diagnosed with RH. Patients’ baseline characteristics are presented in Table 1, Table 2. We found no differences between groups regarding age, gender, body mass index (BMI), biochemical parameters, and comorbidities; however, the RfH subgroup presented greater prevalence of black race and white–coat effect. Similar results were found when comparing the RfH subgroup with only the controlled resistant hypertensives—data presented

Discussion

This study evaluated the prevalence of RfH and factors associated with it, according to a recently proposed definition for this condition, in patients previously considered only resistant hypertensive.6, 7 Some characteristics of this subgroup have been described; however, these findings were from data drawn from population cohort studies designed for other purposes,6 or with a different definition of refractory.2

We have found a 31% prevalence of RfH among our RH population. This prevalence is

References (20)

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This study was supported by the São Paulo Research Foundation (Fapesp), São Paulo, Brazil, and National Council for Scientific and Technological Development (CNPq), Brazil.

Conflict of interest: none.

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