Classification of Blood Pressure and Diagnosis of Hypertension
In 2003, the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) published a classification of BP for adults aged 18 years or older. The November 2017 ACC/AHA guidelines update this classification. Normal blood pressure is still defined as blood pressure that is less than 120/80 mm Hg. The prehypertension category has been eliminated entirely. Elevated blood pressure is now classified as systolic blood pressure between 120–129 mm Hg and diastolic blood pressure less than 80 mm Hg. Stage 1 hypertension is defined as systolic BP between 130–139 mm Hg or diastolic BP between 80–89 mm Hg. Stage 2 HTN refers to systolic BP of at least 140 mm Hg or diastolic BP of at least 90 mm Hg (Table 3-1). These classifications are based on the average of 2 or more properly measured seated BP readings during each of 2 or more office visits or other outpatient assessments such as ambulatory blood pressure monitoring or home blood pressure monitoring with an approved device.
Table 3-1 2017 Blood Pressure Classification
In 10%–15% of patients, BP increases only while in a physician’s office; these patients are said to have “white coat” hypertension. Home BP monitoring or 24-hour ambulatory BP measurement (ABPM) is warranted in these individuals and in patients with labile hypertension, resistant hypertension, hypotensive episodes, or postural hypotension, as well as in patients with masked hypertension (normal blood pressure in the office setting but abnormal readings at home). ABPM, which is more widely used in Europe, provides data on circadian variations of BP. ABPM readings are usually lower than measurements taken in a physician’s office, and they correlate better with target-organ injury than do office measurements. BP in most individuals decreases by 10%–20% during sleep (dipping pattern); those without such a decrease (nondipping pattern) are at greater risk for cardiovascular and neurovascular events. Masked hypertension may occur in 10%–30% of patients and carries a worse prognosis than white coat hypertension with regard to the development of atherosclerosis. Thus, it is important to recognize that a normal office BP does not exclude hypertension. Individuals with a mean self-measured daytime BP above 135/85 mm Hg or a nighttime BP of 120/70 mm Hg at home are generally considered to be hypertensive.
Chobanian AV, Bakris GL, Black HR, et al; National Heart, Lung, and Blood Institute Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure; National High Blood Pressure Education Program Coordinating Committee. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: the JNC 7 report. JAMA. 2003;289(19):2560–2572.
Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA Guideline for the prevention, detection, evaluation and management of high blood pressure in adults: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Hypertension. 2018; 71(6):e13–e115.
Excerpted from BCSC 2020-2021 series: Section 1 - Update on General Medicine. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.