Τhe European and American guidelines in the detection of hypertension phenotypes: The no-deal under the light of clinical practice

The American College of Cardiology and American Heart Association as well as the European Society of Hypertension and European Society of Cardiology have recently updated their recommendations for hypertension.^1,2 American and European guidelines disagree for the cut-off values in the definition of hypertension for the first time. American guidelines proposed lower values for normal blood pressure (BP) creating a difference of 10 mm Hg in the office BP measurements (OBPMs), 5 mm Hg in 24-hour ambulatory BP measurements (ABPMs) and home BP measurements (HBPMs) from the European guidelines. As a result, a patient may be classified as hypertensive according to the American guidelines and normotensive according to European guidelines.^1,2

To our knowledge, there is no study comparing the latest guidelines from Europe and America for their agreement in the detection of the four hypertension phenotypes, and especially white coat hypertension (WCHT) and masked hypertension (MHT), the two most interesting phenotypes as they require a different approach regarding treatment and follow-up. Hence, this was the aim of our study in order to analyse how these differences are reflected in clinical practice. Our secondary aim was to evaluate the agreement between HBPM and ABPM for both European and American guidelines.

The study population for this cross-sectional study consisted of 228 consecutive patients, aged more than 18 years old, who were referred to the Hypertension-ABPM Center of Excellence at the 3rd Department of Internal Medicine, Aristotle University, Greece.

According to the latest guidelines of the European Society of Hypertension and European Society of Cardiology,³ participants were divided into the four phenotypes by combining the cut-off values for OBPMs and daytime ABPMs: true normotensive subjects (OBPM < 140/90 mm Hg and ABPM < 135/85 mm Hg), WCHT (OBPM ≥ 140/90 mm Hg and ABPM < 135/85 mm Hg), MHT (OBPM < 140/90 and ABPM ≥ 135/85 mm Hg) and true hypertensive (OBPM ≥ 140/90 mm Hg and ABPM ≥ 135/85 mm Hg). Similarly, participants were divided based on the cut-off values for OBPMs and HBPMs, with ΗΒPM < 135/85 mm Hg being considered as normal. According to the latest guidelines of the American College of Cardiology and American Heart Association,¹ participants were also divided into the four phenotypes of hypertension based on the OBPM as well as either the HBPM or ABPM and taking into account as increased BP the values of OBPM ≥ 130/80 mm Hg, day ABPM ≥ 130/80 mm Hg and HBPM ≥ 130/80 mm Hg.

The descriptive statistics of our population are depicted in Supplementary Material 1. Cross-tabulation of the results and the agreement between the two methods, HBPM and ABPM, according to each of the guidelines for the definition of hypertension are presented in Supplementary Material 2. Although the results are statistically significant, the general impression is that the HBPM and ABPM do not agree in both guidelines for the detection of the four BP phenotypes. These tools have better agreement in the detection of hypertension and normotension, but poor agreement in the detection of WCHT and MHT. The Kappa index found was lower than 0.35 for the detection of MHT in the European and for WCHT in the American guidelines.

Prevalence of the four phenotypes according to European and American guidelines is reported in Supplementary Material 3. The agreement between guidelines for the detection of the four phenotypes is summarised in Table 1. The agreement between the guidelines was moderate to low by using HBPMs for the established cut-off values of both guidelines. Regarding ABPMs, the agreement between the guidelines ranges between poor for MHT and good for detecting hypertension. Most importantly, the poorest agreement is observed in the identification of WCHT and MHT with both HBPMs and ABPMs.

The results showed that HBPMs and ABPMs have moderate to poor agreement for the definition of MHT and WCHT in both guidelines, whereas the American and European guidelines agreement by using the same diagnostic tool is poor for these two phenotypes. To our knowledge, this is the first study to evaluate the no-deal.

Translating these numbers to everyday clinical practice and taking into account that 1.13 billion of the population worldwide have hypertension,⁴ the poor level of agreement between guidelines and diagnostic tools implies a huge number of patients with different treatment strategies; either treated or just scheduled for regular follow-up, as well as having a different cardiovascular risk estimation. Identifying and treating MHT as well as hypertension is vital as 45% of deaths due to heart disease and 51% of deaths due to stroke are related to complications of hypertension.⁵ Besides the importance of organ damage, another crucial topic is reported; almost 10% more people should receive antihypertensive treatment according to the American guidelines compared to the European, exploding the annual treatment costs in the Swiss health system.⁶ Taking into account the MHT as a population needing treatment, this percentage is even higher in our data. Specifically, 14.9% more people should receive antihypertensive treatment according to the ABPM, and 18.8% according to the HBPM.

Εven if physicians usually follow one distinct guideline in their clinical practice, still this no-deal causes precariousness and raises queries about over- or under-treated patients. Scientists should carefully consider the huge number of patients who can be classified differently and work together for common thresholds in the definition of hypertension. Furthermore, other important clinical parameters such as lifestyle changes in the ‘grey zone’ patients, differentiating cardiovascular risk scores for low income countries and interventions in the younger population should be taken into account.⁷

A limitation of the study is the relatively small population sample. The study included only Caucasian patients and the results may not be extended to other ethnicities. On the other hand, a strength of our study is that all patients were evaluated with the same devices, duration and number of BP readings. Furthermore, the fact that our patients did not receive antihypertensive therapy is a strong advantage.

To conclude, the results of the present study depict the disagreement of American and European guidelines in clinical practice, especially in the identification of WCHT and MHT, independently of the diagnostic tool. These findings can be easily connected with the inconvenience of clinicians, raising queries as to whether their patients are treated properly or not. The disagreement should be tested in larger scale population samples, but this study could be a first step suggesting the need of an agreement between the two most-known hypertension guidelines.

Supplementary material

Supplementary material is available at European Journal of Preventive Cardiology online.

Author contribution

CA: Responsible for BP measurements, proposed the structure of the paper, formulated the paper. ID: Proposed the idea, performed the statistical analysis. GK: Responsible for BP and c-f measurements, contributed to study design SS: Critically appraised the paper, made final suggestions. VK: Critically appraised the paper, made final suggestions.

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship and/or publication of this article.

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