Last year, the American College of Cardiology and American Heart Association updated its clinical guidelines for high blood pressure treatment – increasing the number of Americans diagnosed with high blood pressure. Here, Assistant Professor in the Department of Health Services Administration and Policy Gabriel S. Tajeu outlines what these changes mean for everyday Americans and how the new guidelines could impact public health.
The American College of Cardiology and American Heart Association (ACC/AHA) have updated US clinical practice guidelines for high blood pressure treatment in the recently published 2017 ACC/AHA Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults. This report updates guideline recommendations from the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC7), published in 2003.
While there are nuanced differences between the older JNC7 blood pressure guidelines and the new ACC/AHA 2017 guidelines, the major change is lowering the threshold for diagnosing hypertension from a systolic blood pressure (SBP) of 140 mm Hg or a diastolic blood pressure (DBP) of 90 mm Hg (140/90 mm Hg), to a threshold of 130/80 mm Hg.
The new blood pressure categories are as follows:
- Normal: Less than 120/80 mm Hg;
- Elevated: SBP between 120-129 and DBP less than 80;
- Hypertension - Stage 1: SBP between 130-139 or DBP between 80-89;
- Hypertension - Stage 2: SBP at least 140 or DBP at least 90 mm Hg;
- Hypertensive crisis: SBP over 180 or DBP over 120.
There are several reasons for lowering the threshold for defining hypertension. First, studies over the past few decades have provided clear evidence that as blood pressure increases, so too does the risk of cardiovascular disease (CVD) events such as heart attack and stroke, even at relatively low blood pressures (i.e., above a SBP/DBP of 115/75 mm Hg). Also, among adults who are already receiving antihypertensive medication for high blood pressure, treating blood pressure to thresholds lower than the old JNC7 recommendation of 140/90 mm Hg has been shown to reduce risk in clinical trials and observational studies. Therefore, earlier detection and management of high blood pressure at lower levels is anticipated to be effective at reducing the overall population risk for CVD, which is important; high blood pressure is the leading risk factor for preventable death and disability in the US and globally.
While the percentage of US adults diagnosed with high blood pressure will increase from 31.9% to 45.6% due to the lowered blood pressure threshold, the number recommended for antihypertensive medication is estimated to increase by less than 2% (from 34.3% to 36.2%), according to one study. For Stage 1 hypertension, lifestyle changes including diet and exercise are recommended when the risk of a CVD event is low, for instance among younger adults who do not smoke or do not have diabetes. These patients are not expected to be prescribed antihypertensive medication, but an earlier diagnosis of hypertension will allow physicians the opportunity to seriously discuss the benefits of diet and exercise with patients and potentially slow the progression of hypertension.
Physicians will also be able to closely monitor patients with Stage 1 hypertension and intervene with medications immediately in the case that lifestyle modification does not control blood pressure. For individuals with Stage 1 hypertension where the risk of a CVD event may be high, such as older adults who may smoke, have diabetes, or high cholesterol, antihypertensive medication will be recommended to control blood pressure to a SBP/DBP level of 130/80 mm Hg. In almost all cases where blood pressure has reached Stage 2 hypertension and above, antihypertensive medication will be recommended in addition to lifestyle modification.
Because of the guideline focus on lifestyle changes for people with Stage 1 hypertension but low CVD risk, as previously mentioned, the number of people in the US who will be prescribed antihypertensive medication will not increase substantially. However, for individuals who are already classified as having hypertension according to the previous guidelines (SBP/DPB ≥ 140/90 mm Hg), doctors may recommend more intensive treatment of blood pressure using a combination of additional antihypertensive medications and lifestyle changes in order to control patients’ blood pressure to the new goal of 130/80 mm Hg.
The new ACC/AHA changes to the hypertension guidelines have the potential to improve the health of the US population. More aggressively treating hypertension and lowering the overall blood pressure of the population is anticipated to result in decreased rates of CVD such as heart attack and stroke, leading causes of death and a significant source of healthcare expenditure in the US. Future studies will likely explore the health and economic impact of the new guidelines in the US, how to improve care among adults already diagnosed with hypertension, and determine ways to improve the identification of adults at risk for hypertension and CVD at earlier ages.