Hypertension – can we agree on diagnostic and therapeutic thresholds?Prof. Richard McManus - Oxford, UK
General practitioners from about 20 European countries travelled to Barcelona to attend the Annual EPCCS CV Summit for Primary Care. In addition to the lively discussions and interaction between primary care physicians of different corners of Europe, an important objective of this summit is to produce guidance documents specifically aimed at primary care. Sessions were set up in such a way that not only the current evidence on a subject was reviewed, but that specific considerations for primary care were discussed and challenges and gaps in the evidence were identified. These sessions focused on diabetes and vascular care, managing lipids, hypertension and heart failure. Based on the sessions, EPCCS guidance documents will be written.
Prof. Richard McManus (Oxford, UK) started his presentation with an overview of major guidelines, which until 2017, all defined hypertension as 140/90 mmHg in the office or 135/85 mmHg measured at home. In 2017, however, the ACC/AHA Guideline for High Blood Pressure redefined hypertension as stage 1 hypertension with systolic blood pressure (SBP) between 130-139 mmHg and stage 2 hypertension if SBP ≥140 mmHg. This is based on observations in treatment trials and the increase in CV endpoints with increased BP. McManus thinks, however, that choosing a threshold is arbitrary, since the different thresholds have not been extensively tested in dedicated trials. The bottom line is though that for every 10 mmHg increase, there is a 38% increased stroke risk and 18% CHD risk.
The 2013 ESH/ESC Hypertension Guidelines recommend office measurement of BP for screening and diagnosis of hypertension. However, out-of-office measurements may be considered under certain circumstances, which in reality can be translated to almost all patients. In the US, changes in the guidelines have now resulted in recommendations of out-of-office measurements for diagnosis and ongoing management of hypertension.
This change in recommendation followed the demonstration that routine measurements are often flawed, as BP varies through the day and between seasons. Multiple measurements give a better estimate of the mean BP. Many factors affect BP measurement, such as talking, alcohol intake, wrong size cuff, etc. Moreover, it has been demonstrated that SBP is 7 mmHg lower when a nurse measures it, as compared with when it is measured by GP.
Hypertension is diagnosed based on clinical measurement, but readings can be flawed and therefore it can take weeks/months to make a diagnosis. It should be noted that routine clinic BP measurements are not as accurate as in hypertension trials. Ambulatory BP monitoring (ABPM) results in a better measure of the usual BP and it is considered the gold standard for diagnosis and the most cost-effective method. ABPM can help to detect white coat and masked hypertension, but may not be available for all. Additionally, it is poorly tolerated by some, as it can disturb sleep and activities. Pre-screening of who will likely benefit from ABPM might partially solve this issue. In addition, predictors of the home-clinical difference of BP reduce the need for ABPM. The PROOF-BP online calculator is such a screening algorithm and can help in identifying persons in whom ABPM is necessary. A meta-analysis of 25 trials showed that increased intensity of co-intervention, such as combining self-monitoring with various forms of telemonitoring, resulted in increased efficacy in terms of BP control. Thus, a firm evidence base now supports using home monitoring for long-term management.
The 2013 ESH/ESC guidelines for the management of hypertension recommend an SBP goal of <140 mmHg, whereas the 2017 ACC/AHA guidelines redefined hypertension and the treatment target to <130/80 mmHg. The latter change was mainly based on the results of the SPRINT trial, which showed a significant reduction in the primary outcome, a composite of CV events including CV death, with intensive treatment (SBP <120 mmHg) vs standard treatment (SBP <140 mmHg) in patients with hypertension and increased CVD risk, but without diabetes. Individuals >75 years showed similar results . The SPRINT trial used automated clinic BP measurement, with three mostly unattended readings, after the participant had rested for five minute. In the overall study population, there were more adverse events, such as hypotension and syncope, in the intensive treatment group compared to the standard group.
Similar results were observed in the ACCORD trial, which enrolled patients similar to the SPRINT population, but with type 2 diabetes. Here, the primary outcome of nonfatal MI, nonfatal stroke or CV death was not significantly reduced with intensive vs. standard therapy, and adverse events, among which hypotension, arrhythmia and hyperkalemia, were significantly more frequent with intensive therapy.
In the SPS3 trial, patients with recent lacunar stroke were randomized to a SBP target of 130-149 mmHg vs <130 mmHg. Results showed no significant difference in the primary outcome of stroke, although a tendency was seen towards a reduction of stroke in the lower-target group. There was no difference in harm between the two groups.
The HOPE-3 trial, finally, was done in individuals with intermediate-risk and without CVD, with two different randomizations: BP treatment vs no BP treatment, and statins vs no statins. BP was reduced in the BP-treatment group, but a subanalysis showed that individuals with stage 1 hypertension actually had stage 2 hypertension and should have been treated with antihypertensive medication. Finally, a meta-analysis did not support treatment for primary prevention in patients with SBP <140/90 mmHg.
In conclusion, the results of the SPRINT trial showed that employing a threshold <130/80 mmHg to treat BP is beneficial, but it should be noted that in SPRINT, 90% of patients were already taking antihypertensive drugs at baseline. The ACCORD trial and SPS3 trial confirmed these results, although these studies may have been underpowered. The HOPE-3 trial suggests that a target <140 mmHg in intermediate-risk individuals is not helpful. The HOPE-3 data also suggest that current thresholds for treatment are appropriate for primary prevention. In addition, a meta-analysis did not support treatment <140/90 mmHg for primary prevention.
Mark van der Wel (Nijmegen, The Netherlands) ended this session with a practical workshop on ABPM. He discussed the challenges in BP measurements and explained how training of staff in the protocol takes time and effort, but results in better practice of BP measurements. He continued by asking the audience whether they used ABPM for their patients, followed by a discussion on how patients should use it, what to do with error readings, when to use it and how to select data from the readings.
We will compose an EPCCS Guidance Document on this topic, based on this session (presentation and discussion) during the EPCSS CV Summit 2018 in Barcelona.