The 2017 hypertension guidelines take pains to point out that the way blood pressure has often been measured in doctors’ offices, and the way hypertension has been typically diagnosed, has been fraught with problems.
A persons’s blood pressure fluctuates markedly during the course of a normal day, depending on a person’s state of activity, stress, hydration, posture, and several other factors that can change from minute to minute. So, in order to accurately measure blood pressure, it is important to do so under carefully controlled conditions.
In effect, the 2017 hypertension guidelines split the previous “prehypertension” category into two categories. The lower half is still considered to be prehypertension, but the upper half (systolic blood pressure of 130-139) is now regarded as Stage 1 hypertension. This change was made because data from clinical trials now clearly shows that people whose blood pressures are in this 130-139 range have a substantially higher risk of cardiovascular complications, and their elevated blood pressures should be addressed.
Here is how the new guidelines describe the correct procedure for measuring blood pressure:
The patient should be completely relaxed, sitting in a chair (with feet on floor and the back supported) for at least 5 minutes.
The patient should avoid caffeine, exercise, and smoking for at least 30 minutes before the measurement is made.
The patient should have an empty bladder.
Neither the patient nor the person taking the blood pressure should talk during the rest period, or during the measurement.
All clothing covering the location of the blood pressure cuff should be removed. (No taking of blood pressure over a sleeve.)
In particular, the blood pressure should not be measured while the patient is sitting or lying on an examination table.
At least 2 or 3 measurements should be taken, on at least 2 or 3 separate occasions, and an average of these readings should be used to diagnose hypertension.
Anyone who has been to a doctor’s office in recent years will probably recognize that these guidelines are rarely followed. Yet, they need to be followed in order for the blood pressure readings to be accurate. This was always true, but it is especially true today with the more aggressive hypertension classification system recommended in the 2017 guidelines. Unless the blood pressure is measured under the conditions of quiet, comfortable rest described in these guidelines, odds are that blood pressure recordings will be falsely elevated.
In addition, the 2017 hypertension guidelines recommend that if hypertension is found in the clinic using these careful measurement steps, the blood pressure should be measured on an ambulatory basis before determining that hypertension is present.
Taking Overall Cardiovascular Risk Into Account
While people whose systolic blood pressure is between 130-139 mmHg are now classified as having Stage 1 hypertension instead of prehypertension, the 2017 hypertension guidelines recommend taking their overall cardiovascular risk into account before deciding whether or not to place them on antihypertensive treatment.
In estimating the overall cardiovascular risk of people with Stage 1 hypertension, the 2017 guidelines recommend using the ACC/AHA Pooled Cohort Equations risk calculator. This calculator estimates the 10-year risk of cardiovascular disease using age, race, sex, cholesterol levels, systolic blood pressure, diabetes and smoking history, and any treatment for cholesterol and blood pressure. If the 10-year risk based on this risk calculator is estimated to be above 10 percent, then drug treatment for Stage 1 hypertension is recommended.
If their 10-year risk is lower than 10 percent, people with Stage 1 hypertension should be treated with lifestyle changes, like those with prehypertension.
People with Stage 2 hypertension will almost invariably require drug therapy.
Emphasis on Lifestyle Changes
For anyone who has either prehypertension, or Stage 1 or Stage 2 hypertension, lifestyle changes are emphasized as the cornerstone of therapy by the 2017 guidelines.
Recommended lifestyle changes include plenty of exercise (at least 30 minutes of exercise at least three times per week), a DASH-style diet, reducing dietary sodium, smoking cessation, weight loss, and limiting alcohol to no more than one drink per day for women, and two drinks per day for men.
Lower Targets for Blood Pressure Therapy
The 2017 guidelines emphasize that the target for blood pressure treatment should be a systolic pressure of less than 130 mmHg, and a diastolic pressure of less than 80 mmHg.
This target is lower than the targets proposed by previous guidelines, which most typically aimed for a systolic blood pressure of less than 140 mm Hg for most people. Some previous guidelines urged more caution in elderly patients, recommending a treatment goal of 150 mmHg or less.
The new, lower treatment target of 130 mmHg or less, for elderly people and for everyone else, was based on the results of newer, larger randomized clinical trials which showed improved outcomes for people of all ages treated to the lower targets.