Blood pressure is the force exerted by circulating blood against the walls of the arteries. This measurement is a fundamental indicator of cardiovascular health, as consistently high pressure can damage blood vessels and organs over time. Medical understanding of the ideal pressure range and diagnostic thresholds is continuously developing, driven by new scientific evidence. This evolution leads to periodic revisions of clinical guidelines to ensure the best possible health outcomes. The most significant recent shift occurred in 2017, dramatically altering how millions of adults are diagnosed and treated.
The Foundational System
For decades, blood pressure management standards in the United States were set by the Joint National Committee (JNC) reports. The Seventh Report (JNC 7), published in 2003, established the primary framework used by clinicians for over a decade. JNC 7 defined normal blood pressure as less than 120/80 mmHg.
The JNC 7 guidelines set the threshold for Stage 1 Hypertension at 140/90 mmHg or higher. Readings between 120/80 mmHg and 139/89 mmHg were categorized as “Prehypertension,” a warning stage requiring lifestyle modifications. The primary treatment goal for most adults was to lower blood pressure below 140/90 mmHg.
This system was challenged by the JNC 8 report in 2014, which created professional disagreement. JNC 8 suggested a less stringent approach for older adults, recommending a higher threshold of 150/90 mmHg for initiating drug treatment in people aged 60 or older. This recommendation was viewed as a step back from the established target, highlighting the need for a definitive, evidence-based trial to settle the debate.
The Evidence That Triggered Guideline Revision
The definitive evidence that fueled the guideline change came from the Systolic Blood Pressure Intervention Trial (SPRINT). This large-scale, randomized clinical trial began in 2010, enrolling over 9,300 participants aged 50 or older who were at increased risk for cardiovascular disease. The trial was specifically designed to compare the health outcomes of two different treatment strategies.
One group, the standard treatment arm, was managed to the conventional target of less than 140 mmHg systolic blood pressure. The second group, the intensive treatment arm, was managed to a much lower systolic target of less than 120 mmHg. Participants in the intensive group typically required a higher average number of medications to achieve this lower goal.
The trial was stopped early in 2015 because the results for the intensive group were overwhelmingly positive. SPRINT demonstrated that aiming for the lower systolic target significantly reduced the rate of major cardiovascular events (such as heart attack, stroke, and heart failure) by 25%. Furthermore, the intensive treatment reduced the overall risk of death from any cause by 27% compared to the standard treatment group. These findings provided a strong scientific basis that a lower blood pressure target was more protective.
The Landmark 2017 Redefinition of Hypertension
The groundbreaking results of the SPRINT trial led the American College of Cardiology (ACC) and the American Heart Association (AHA) to completely overhaul the guidelines. In November 2017, these organizations published new guidelines that fundamentally changed the definition of high blood pressure for all adults. The threshold for diagnosing hypertension was lowered from the long-standing 140/90 mmHg to 130/80 mmHg.
This revision meant millions of Americans previously classified as having “Prehypertension” were now officially diagnosed with hypertension. The new guidelines created a more granular system of categories to better stratify risk. Normal blood pressure remained defined as less than 120/80 mmHg.
A new category, “Elevated,” was introduced for systolic pressures between 120 and 129 mmHg (with diastolic less than 80 mmHg). Stage 1 Hypertension was defined as 130–139 mmHg systolic or 80–89 mmHg diastolic. The old 140/90 mmHg threshold was reclassified as Stage 2 Hypertension. This shift was designed to identify and intervene with people at lower pressure levels who face increased cardiovascular risk.
Practical Impact on Diagnosis and Treatment Goals
The immediate consequence of the 2017 guideline change was a dramatic increase in the number of adults diagnosed with high blood pressure. Estimates suggested the overall prevalence of hypertension in the adult population increased from approximately 32% to 46%. However, for many individuals, this new diagnosis of Stage 1 Hypertension did not immediately translate into a prescription for medication.
The guidelines emphasize that initial management for those with Stage 1 Hypertension and low cardiovascular risk is intensive lifestyle modification. This non-pharmacological approach includes weight loss, a healthy diet, regular exercise, and reduced sodium intake, typically given a three-to-six-month trial period. Lifestyle changes alone can often achieve the necessary reduction in blood pressure and mitigate the need for drug therapy.
Medication is recommended immediately for those with Stage 1 Hypertension only if they have pre-existing cardiovascular disease, chronic kidney disease, diabetes, or a high 10-year risk of heart disease (10% or greater). For all patients started on medication, the new target goal is generally less than 130/80 mmHg. Achieving this lower goal requires diligent monitoring and often a combination of two or more medications.