Effects of Blood Pressure Measurements on Mortality FREE

Blood pressure measures the force of blood against artery walls. Usually, people use 2 numbers to describe blood pressure. Systolic blood pressure is the higher and the first number. It measures the force of blood against the artery walls as the heart contracts to pump blood through the body. Diastolic blood pressure is the lower and second number. It measures the force that remains in artery walls when the heart relaxes and fills with blood. A third way to describe blood pressure is pulse pressure, the difference between the systolic and the diastolic blood pressure readings. Wide pulse pressures, or large differences between systolic and diastolic blood pressure numbers, may indicate stiff and injured arteries.

Health dangers associated with abnormal blood pressure may vary depending on which blood pressure measurement is used. Many studies show that high systolic and diastolic blood pressure levels increase risk for death, kidney disease, strokes, heart attacks, and heart failure. Several studies also show that wide pulse pressure, particularly in older adults, increases risk for heart problems and death. Sorting through which of the 3 measures is most closely related to which health danger is difficult.

To find out which blood pressure measurements are most useful in determining risk for death.

7830 adults older than 30 years of age who had participated in the Second National Health and Nutrition Examination Survey (NHANES II). No participant had heart disease at first examination.

A representative sample of U.S. adults was interviewed and examined between 1976 and 1980. Participants were asked about personal characteristics, medical history, current and past medicine use, and health behaviors. Participants' blood pressure was measured carefully, and blood samples were obtained to measure cholesterol levels. Then, from 1976 to 1992, Social Security and National Death Index files were searched to see whether any participants had died and to find causes for death. The researchers then looked at which blood pressure measurements (systolic blood pressure, diastolic blood pressure, or pulse pressure) taken at the first examination predicted deaths. To help ensure correct predictions, they did analyses that “controlled for” other factors, such as age, sex, smoking status, diabetes, and cholesterol level, which might be associated with increased risk for death.

Increasing levels of systolic blood pressure were associated with increasing risk for death in a continuous manner. Increasing levels of diastolic blood pressure greater than 80 mm Hg were associated with increasing risk for death. In people younger than 65 years of age, risks associated with diastolic blood pressure were flat (similar) for levels less than 80 mm Hg. In people older than 65 years of age, risk for death was increased with very low diastolic blood pressure. Relationships between wide pulse pressure and death were complex. They depended on whether the widened pulse pressure was due to increased systolic or decreased diastolic blood pressure.

Blood pressure was taken on a single day at the first examination. It may not have reflected the usual blood pressure of participants over time.

Associations between wide pulse pressure and death are complicated. They depend on whether the wide pulse pressure is due to increased systolic or decreased diastolic blood pressure.