ESSENTIALS OF DIAGNOSIS
Primary hypertension in adults aged 18 years and older is defined as blood pressure of 140/90 mm Hg or more, based on an average of two or more properly measured seated blood pressure (BP) readings at each of two or more clinic visits.
Normal BP is a systolic BP (SBP) <120 mm Hg and diastolic BP (DBP) <80 mm Hg.
Prehypertension is defined as an SBP of 120–139 mm Hg or DBP of 80–89 mm Hg.
Stage 1 hypertension is defined by an elevation in either SBP 140–159 mm Hg or diastolic BP of 90–99 mm Hg.
Stage 2 hypertension is defined by an elevation in either SBP of ≥160 mm Hg or DBP of ≥100 mm Hg.
The BP should be measured properly (see text) and on at least two separate occasions before confirming the diagnosis. It should also interpreted in the context of the overall cardiovascular risk of the patient, which is most easily estimated by evaluating other concomitant disorders and target-organ damage (TOD) and using the lifetime risk equation (http://clincalc.com/cardiology/ascvd/pooledcohort.aspx or http://professional.heart.org/professional/GuidelinesStatements/Prevention_Guidelines/UCM_457698_Prevention-Guidelines.jsp)
Hypertension affects 29% of all adult Americans and its prevalence increases with age. Indeed, data from the Framingham health study suggest that people with a normal BP (<120/80 mm Hg) at 55 years of age have a 90% lifetime risk of developing hypertension. Additionally, it is now well established that a linear relationship exists between BP and risk of cardiovascular events, thus the more elevated the BP the greater the likelihood of myocardial infarction, congestive heart failure, kidney failure, or stroke.
Despite the increased prevalence of hypertension and its associated morbidity and mortality, current control rates are inadequate. Despite the availability of multiple treatments only 53% of people with hypertension have their BP controlled to a goal of less than 140/90 mm Hg. Key factors for the inadequate BP control include failure of physicians to prescribe: (1) lifestyle modifications, (2) adequate doses of antihypertensive medications, and (3) appropriate drug combinations and increased occurrence of pure systolic hypertension in the elderly, which is considerably more difficult to treat.
The American Heart Association recommends that specific public health interventions such as eating a diet high in vegetables and fruits, reducing sodium intake, and increasing physical activity be strongly encouraged. This strategy can achieve a downward shift in the distribution of a population’s BP and thus potentially decrease the lifetime risk of morbidity and mortality from hypertension in an individual.
A. Measurement of Blood Pressure
Accurate measurement and interpretation of BP is crucial for the diagnosis and treatment of hypertension. The recommendations outlined below will help standardize the technique and improve the accuracy of BP readings (see Essentials of Diagnosis):