Isolated systolic hypertension, defined as systolic blood pressure of 140 mm Hg or greater with a diastolic blood pressure below 90 mm Hg, is known to be associated with an increase of risk of coronary heart disease and stroke. The HANES I group estimated that isolated systolic hypertension, uncommon under 54 years of age, occurred in 5 percent to 10 percent of adults over 55 years and was less common than systolic-diastolic elevation. Evidence was not readily available that there was effective and safe therapy to correct isolated systolic hypertension. At that time, there was no body of clinical or research data that conclusively proved that such therapy, if available, was beneficial.