Definition of Hypertension
Hypertension is defined as a systolic blood pressure ≥130 mmHg or a diastolic blood pressure ≥80 mmHg, based on an average of two or more measurements obtained on two or more separate occasions. 1, 2
Blood Pressure Classification
The current classification system, established by the American College of Cardiology/American Heart Association and adopted by the American Diabetes Association, includes the following categories:
- Normal BP: Systolic <120 mmHg AND diastolic <80 mmHg 2, 3
- Elevated BP: Systolic 120-129 mmHg AND diastolic <80 mmHg 1, 3
- Stage 1 Hypertension: Systolic 130-139 mmHg OR diastolic 80-89 mmHg 2, 3
- Stage 2 Hypertension: Systolic ≥140 mmHg OR diastolic ≥90 mmHg 2, 3
Diagnostic Requirements
Blood pressure should be measured at every routine clinical visit, and elevated readings must be confirmed with multiple measurements on separate days before diagnosing hypertension. 1 The exception is for individuals with blood pressure ≥180/110 mmHg who have existing cardiovascular disease—these patients can be diagnosed with hypertension at a single visit. 1
Proper Measurement Technique
Blood pressure must be measured correctly to ensure accurate diagnosis: 1
- Patient seated with feet flat on floor and arm supported at heart level
- After 5 minutes of rest
- Appropriate cuff size for upper arm circumference
- Measurements should be obtained by a trained individual
Out-of-Office Confirmation
Home blood pressure monitoring or 24-hour ambulatory blood pressure monitoring should be used to confirm the diagnosis and detect white coat hypertension (elevated office BP but normal out-of-office BP) or masked hypertension (normal office BP but elevated out-of-office BP). 1, 3 This is particularly important because white coat hypertension carries cardiovascular risk similar to normal BP, while masked hypertension carries risk equivalent to sustained hypertension. 3
Important Context: European vs. American Definitions
A critical caveat exists: The European Society of Cardiology/European Society of Hypertension uses different cutpoints, defining hypertension as systolic BP ≥140 mmHg or diastolic BP ≥90 mmHg. 4, 5 This creates a significant divergence in practice between North America and Europe, with the American definition identifying approximately 14% more adults as hypertensive. 4, 2
Special Populations
For adolescents ≥13 years of age, the same adult definition applies (≥130/80 mmHg), aligning pediatric and adult guidelines. 6 For children <13 years, hypertension is defined as BP ≥95th percentile for age, sex, and height. 6
Clinical Implications
The 130/80 mmHg threshold was adopted because adults with BP in this range have approximately 2-fold increased cardiovascular disease risk compared to those with normal BP, and randomized trials have demonstrated benefit with systolic BP targets below 130 mmHg. 3 This definition change increases hypertension prevalence in the U.S. from 32% to 46%, but importantly, most newly classified individuals require lifestyle modification rather than immediate pharmacological therapy. 2