Research ArticleRefractory and resistant hypertension: characteristics and differences observed in a specialized clinic
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
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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.