Perspectives on isolated systolic hypertension in elderly patients.

Until the mid-20th century, clinicians' concern was directed mainly to the systolic component of blood pressure. Later, however, when systolic blood pressure was found to be elevated with advancing age and decreased compliance of the arterial wall, it began to be considered an inevitable consequence of aging. Based on this belief, physicians often concluded that only the diastolic blood pressure elevation, which reflected peripheral vascular resistance, was harmful, while systolic hypertension was innocuous. Therapeutic intervention was practiced mainly for diastolic hypertension, and research protocols were based on the levels of diastolic blood pressure alone. In the 1950s, even when life insurance companies' actuarial data revealed that systolic and diastolic blood pressure elevations were hazardous to health, few clinicians took heed. In 1962, the World Health Organization also defined hypertension as a blood pressure level of 165/95 mm Hg or higher for intervention purposes. However, until the 1991 Systolic Hypertension in the Elderly Program (SHEP) trial, many physicians were reluctant to pay credence to the need for therapy of elevated systolic blood pressure (vide infra).