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The new high blood pressure definition amidst a paradigm shift

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The high blood pressure definition has changed in the last few days.  That change is part of a paradigm shift on the part of the American Heart Association, the American College of Cardiology and nine other medical groups.  On November 13, 2017 the joint group released a new comprehensive guideline which contained recommendations for prevention, detection, evaluation and management of high blood pressure (BP) in adults.

In addition to changing the definition of hypertension (high blood pressure) the new guideline also includes:

  • Revised categories of blood pressure levels
  • An emphasis on self-measured blood pressure monitoring
  • New treatment recommendations for the different blood pressure levels

The new definition of high blood pressure

Hitherto, high blood pressure was considered to be a reading of 140/80 or greater. Under the new guideline though, it is now a reading of 130/80 or greater.  It applies to either the systolic (top number) reading, diastolic (bottom number) reading, or both numbers.  

What is normal blood pressure?

The readings that define a normal blood pressure have not changed with the new guideline.  They are still less than 120 for the top number and less than 80 for the bottom number.  It is important not to confuse a normal blood pressure with a target blood pressure though.  The former applies to someone who does not have hypertension.  The latter pertains to people with hypertension.

 The target blood pressure varies depending on a number of factors.  But according to the new guideline, in patients with known cardiovascular disease or a greater than 10% risk of experiencing a cardiovascular acute event such as MI, stroke, or heart-related death over a 10-year period of time, it is less than 130/80.

Blood pressure values and classification

In keeping with the new guideline a systolic reading between 120 and 129 with a diastolic reading of less than 80 is still elevated BP.  But the pre-hypertension category no longer exists. Instead, a systolic reading between 130 and 139 and a diastolic reading between 80 and 89 is now stage 1 hypertension.  Stage 2 hypertension is a systolic reading of 140 or greater and/or a diastolic reading of 90 or greater. The table below is a summary. high blood pressure definition

Reasons for the changes

The new guideline is the first update in 14 years.  The reason for the changes was the results of data from research trials which showed that people in the lower blood pressure (BP) ranges also have an increased risk of heart and blood vessel disease, death and disability.  

The chief source of the data was the SPRINT trial.  SPRINT is an acronym for systolic blood pressure intervention trial.  It was a large research study of more than 9,000 individuals 50 years of age and older. The sponsor of the study was the National Heart, Lung and Blood Institute.  The research showed that reducing the top BP number to below 120 rather than to between 140 and 150, as previously recommended, can reduce the risk of heart attack and stroke.  Other studies of younger people have shown that benefit as well.

Impacts of the new high blood pressure definition

As a result of the high blood pressure definition change the percentage of adults in the US now considered to have high blood pressure is 46%.  This is a 14% increase from the prior 32%.  That translates into almost half of the adults in the US now having high blood pressure. The prior figure had been one third. It’s not that the new cases didn’t exist before. They just weren’t recognized.  With the change in the high blood pressure definition, the estimated number of Americans with hypertension is now 103 million.

Studies have shown that BP control in Americans taking medication for hypertension is an estimated 54%.  That means 46% are not controlled. Bearing in mind that the number of people with undiagnosed hypertension just increased with the new guideline, the overall percentage of poor control is now even higher because of the lack of treatment of the new cases.  

Self-measured blood pressure monitoring (SMBPM)

The ability of patients to perform accurate BP readings outside of a doctor’s office not only confirms a suspected diagnosis of high blood pressure based on office readings.  It also helps avoid missing the diagnosis of masked hypertension and the incorrect diagnosis of hypertension when in fact a patient is showing signs of the white coat phenomenon

In addition, SMBPM engages patients in their treatment; improves the accuracy of BP readings; and promotes patient adherence to treatment.  The expected result is better BP control. 

A very helpful resource for implementing and successfully using SMBPM is Target: BP – a website formed in partnership by the American Heart Association and the American Medical Association.  It supports doctors and care teams by offering access to the latest research, tools, and resources to reach and sustain target blood pressure goals of the patients they serve. Its stated goal is to significantly improve the nation’s blood pressure control rate and to build a healthier America.

New hypertension treatment recommendations

Even though more people will have a diagnosis of hypertension under the new guideline the estimate is that only one in 5 of the 14% increase will need to take medication. The reason is that many in category 1 will require healthy lifestyle changes as the main method of treatment.  Also, the belief is that many cases of hypertension can be prevented with this early intervention.

The table below is a summary of the main new treatment recommendations.

high blood pressure definition The new guideline has not changed the meaning of hypertensive crisis.  It is still a BP of greater than 180/120.  The new guideline contains specific recommendations on how to manage it though.  The table below is a summary.

Hypertensive Crisis Management Recommendations

Hypertensive Urgencysystolic BP > 180 and/or diastolic BP > 120If the patient has not been compliant with taking antihypertensive medication restart it. If the patient has been taking antihypertensive medication as prescribed intensify it. Treat anxiety if applicable.
Hypertensive Urgencysystolic BP > 180 and/or diastolic BP > 120 with target organ damageAdmit patient to an intensive care unit for continuous monitoring of BP. If there is new/progressive or worsening target organ damage, administer a parenteral blood pressure lowering medication.
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