Methods of Assessing blood pressure: identifying threshold and target values (MeasureBP): A Review & Study Protocol

Methods of Assessing blood pressure: identifying threshold and target values (MeasureBP): A Review & Study Protocol

Context

Elevated blood pressure is the number one risk factor world-wide for developing cardiovascular disease leading to death. Also referred to as hypertension, it is responsible for approximately 7.1 million deaths annually and 4.4 % of the global disease burden, including stroke, myocardial infarction, heart failure, and chronic kidney disease.

Hypertension affects almost 30% of all adults worldwide, with current estimates projecting a 60% increase by 2025. The risk of developing hypertension is extremely high; a 55-year-old adult with normal blood pressure has an over 90% risk of developing hypertension before the age of 80.

While hypertension is considered the most costly cardiovascular disease, it is a risk factor that can be managed and controlled. To achieve this, it is critical to take regular and accurate blood pressure measurements, including evidence-based treatment targets, thresholds, and diagnostic algorithms.

Traditionally, blood pressure measurements have been taken using a sphygmomanometer, an instrument consisting of an inflatable rubber cuff applied to the arm and connected to a column of mercury next to a graduated scale. Measurements are taken by increasing and gradually releasing the pressure in the cuff. However, due to environmental concerns these devices are being rapidly replaced by automated alternatives in the office, at home, and for ambulatory monitoring. They are being widely integrated into clinical practice due to their convenience, reliability, and ability to measure blood pressure in unique environments. These automated alternatives (AOBP) refers to an automated series of BP measurements done while the doctor or nurse leaves the patient alone in the room. It has been shown to lower and almost eliminate the “white-coat” effect. Unfortunately, current treatment targets and thresholds are based only on standardized manual measurement techniques performed in clinic or research settings.

Despite progress in automated blood pressure measurement technology, there is limited research linking hard outcomes (cardiovascular events such as heart attack, stroke or death) to automated office blood pressure measurement treatment targets and thresholds. Until outcome-driven targets and thresholds become available for automated measurement methods, deriving evidence-based equivalences between automated and manual methods of measuring blood pressure is the next best solution.

While automated technology is now being recommended by national and international guidelines and has the potential to improve how we assess and manage hypertension, the data linking its use to the success of treatment and potential outcomes such as heart attack or stroke is limited. No randomized, controlled trials using automated devices have been performed to evaluate therapeutic treatment targets and thresholds.

To close the critical knowledge gap, the MeasureBP study group was initiated by the Canadian Hypertension Education Program to define equivalent values between standardized and automated methods of blood pressure measurement. This was achieved through a synthesis and review of available evidence and individual subject-level data.

Objectives

This research paper provides a review of previously written literature on the topic as well as the MeasureBP study protocol. The objective of this is to build a solid, evidenced-based foundation for managing hypertension and to help clarify uncertainties within current blood pressure guidelines.

Results

The study is currently ongoing. Using individual subject-level data, MeasureBP’s overall goal is to assess: How do different automated methods of measuring blood pressure compare with the standardized manual methods?

Results will be shared with the medical community, patients and the general public, and international hypertension societies around the world. Group discussions between MeasureBP knowledge users, key physicians, pharmacists, and nurses will identify the best implementation strategies.

Conclusions

Early detection and management of suboptimal blood pressure levels are crucial to improving outcomes associated with hypertension. This carries a significant impact at both the individual and public health levels. Additionally, alleviating the burden of chronic disease will result in a more cost-effective use of the healthcare system and, thus, better usage of provincial and federal tax resources.

As automated methods to measure blood pressure are being increasingly used in clinical practice, evidence-based treatment targets and thresholds are necessary for optimal management of hypertension. Manual technology has been used by large clinical trials to establish our current hypertension threshold for the general population. However, these thresholds need to be revised to take into account variances in measurements taken by automated devices.

Using individual subject-level data and meta-analyses, MeasureBP aims to address a critical knowledge gap by developing evidence-based equivalences between newer automated devices and standardized manual techniques. This approach is a temporary solution until a large number of properly designed studies and trials can be conducted to fill in the blanks.

Given the importance of this research question and the international scope of impact, the results from MeasureBP are anticipated to have a significant impact on health care providers, policy makers and patients, nationally and internationally.

Research by: Gelfer M, Blom KC1, Farina S, Gomez YH, Campbell NR, Hemmelgarn BR, Cloutier L, McKay DW, Dawes M, Tobe SW, Bolli P,  McLean D, Bartlett G, Joseph L, Featherstone R, Schiffrin EL, Daskalopoulou SS.

Published in Current Hypertension Reports