Blood pressure is the force of blood pushing against the walls of your arteries, measured using two numbers: systolic (pressure when the heart beats) and diastolic (pressure between beats). Medical guidelines for healthy or high blood pressure are not static; they evolve as new research becomes available. Understanding these changes is important because the thresholds determine when a patient is diagnosed with hypertension and when treatment should begin to prevent serious health issues.
The Benchmark Before the Shift
Before the significant shift, the standard for diagnosing high blood pressure was set by the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7). Published in 2003, this report established a classification system that remained the benchmark. Normal blood pressure was defined as less than 120 mmHg systolic and less than 80 mmHg diastolic.
The JNC 7 guidelines introduced “prehypertension,” covering systolic pressures between 120 and 139 mmHg or diastolic pressures between 80 and 89 mmHg. This category alerted patients to their risk and prompted lifestyle modifications. Under these standards, Stage 1 Hypertension was not diagnosed until blood pressure reached 140 mmHg systolic or 90 mmHg diastolic.
For most patients with hypertension, the treatment goal was below 140/90 mmHg. Lower targets (less than 130/80 mmHg) were recommended for certain high-risk groups, such as patients with diabetes or chronic kidney disease. Accumulating evidence eventually began to challenge these thresholds.
Defining the Major Shift
The major shift occurred in November 2017 with the publication of new guidelines from the American College of Cardiology (ACC) and the American Heart Association (AHA). This revision redefined high blood pressure, lowering the diagnostic threshold. The previous category of “prehypertension” was eliminated and replaced by “Elevated” and “Stage 1 Hypertension.”
Under the 2017 ACC/AHA guidelines, the definition of hypertension changed from 140/90 mmHg to 130/80 mmHg. Stage 1 Hypertension is now diagnosed when systolic pressure is between 130 and 139 mmHg or diastolic pressure is between 80 and 89 mmHg. The old threshold of 140/90 mmHg now signifies the start of Stage 2 Hypertension.
This reclassification immediately increased the number of adults diagnosed with hypertension in the United States. The change advocates for lifestyle intervention as the primary treatment for those newly diagnosed with Stage 1 hypertension who are not at high cardiovascular risk. This shift prompts preventive action by making more individuals aware of their elevated risk earlier.
The Scientific Justification
The primary driver behind the 2017 guideline overhaul was data from the Systolic Blood Pressure Intervention Trial (SPRINT). SPRINT was a large clinical trial comparing two blood pressure targets in high-risk adults without diabetes or a history of stroke. One group targeted less than 140 mmHg systolic pressure, while the other targeted less than 120 mmHg.
The trial was stopped early in 2015 due to the positive results in the intensive treatment group. Data showed that treating to the lower systolic target (less than 120 mmHg) significantly reduced the rate of cardiovascular events, such as heart attack and heart failure, by 25%. The intensive treatment group also experienced a 27% reduction in the overall risk of death compared to the standard group.
These findings provided evidence that achieving a lower blood pressure goal offered substantial health benefits. The SPRINT study demonstrated that for many high-risk patients, the long-term benefits of a lower blood pressure goal outweighed the potential risks. This scientific evidence led to the re-evaluation of treatment goals and the lowering of the diagnostic threshold for hypertension.
Current Classification and Practical Impact
The current framework, established by the 2017 ACC/AHA guidelines, uses four main categories to classify blood pressure in adults. Normal blood pressure remains a systolic reading of less than 120 mmHg and a diastolic reading of less than 80 mmHg. The first indication of elevated risk is the new “Elevated” category, defined by a systolic pressure between 120 and 129 mmHg and a diastolic pressure still below 80 mmHg.
Stage 1 Hypertension is now diagnosed at a systolic pressure of 130 to 139 mmHg or a diastolic pressure of 80 to 89 mmHg. Stage 2 Hypertension is defined as a systolic pressure of 140 mmHg or higher or a diastolic pressure of 90 mmHg or higher. A Hypertensive Crisis, which requires immediate medical attention, is a systolic reading over 180 mmHg and/or a diastolic reading over 120 mmHg.
The practical impact for patients is a greater emphasis on lifestyle changes at lower blood pressure readings. For those with Elevated blood pressure, the recommendation is lifestyle modification and re-assessment in three to six months. For many adults diagnosed with Stage 1 Hypertension who have a lower cardiovascular risk, initial treatment remains lifestyle modification alone. Medication is only added if the pressure does not improve after three to six months.
The overarching treatment goal for nearly all adults with confirmed hypertension is a blood pressure of less than 130/80 mmHg. This lower target encourages proactive management of risk factors before they lead to severe cardiovascular complications. The guidelines stress the importance of accurate measurement, confirming the diagnosis using multiple readings over several occasions.