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BLOOD PRESSURE - WHO TO SCREEN AND WHEN

(November 2002)

Investigators from the extraordinary Framingham Heart Study studied the development of high blood pressure over a four-year period in 9,845 men and women, average age 52 years. The participants were divided into three groups at the start of the study:

They then determined what percentage of each group became hypertensive over the four-year followup period. Hypertension was defined as either a systolic pressure of 140 millimeters of mercury or greater, or a diastolic pressure of 90 millimeters or higher. Blood pressure was determined twice after the individual had been sitting quietly for at least five minutes. Either the systolic pressure or the diastolic pressure was used to classify the individual. For example, if a person had a normal systolic pressure of 128 millimeters of mercury, but a high normal diastolic of 85 millimeters, that person was classified as high normal.

The results were surprising in regard to the frequency with which high blood pressure developed in that relatively brief period.

The results were divided into those under and those over age 65 at the start of the study. Of those under age 65,

The results were even more dramatic for those over age 65 at the start of the study:

Weight gain was associated with a higher risk of developing hypertension; a 5 percent gain in weight (8 pounds for a 160-pound man, 7 pounds for a 140-pound woman) increased the risk of developing high blood pressure by 20 to 30 percent.

The authors, on the basis of these results, recommend blood pressure screening annually for those with high normal blood pressures, every two years for those with normal blood pressures or for those over age 65 with optimal blood pressure, and every five years for those under age 65 with optimum blood pressure.

Commentary: This is a terrific study. Still, the frequency of developing high blood pressure in four years for those classified as normal or optimum is surprisingly high, particularly for those over age 65. The high frequency of developing high blood pressure both for those under and those over age 65 needs to be confirmed by other studies.

The recommendations for screening intervals are based on estimates of high blood pressure developing in each of the groups in each of the four years of the study. The four year results are based on actual measurements; the estimates are not. Screening intervals should be based on data, not estimates.

for the evidence that blood pressure needs to be monitored regularly because even those with optimal blood pressure can become hypertensive in a short period of time; also for the evidence that modest weight gain is a major factor in the development of high blood pressure.

The evidence is clear that high normal blood pressure is a risk factor for heart attack and stroke, and it very frequently is followed by the occurrence of frank hypertension which is even more dangerous. The evidence is also clear that a large percentage of those with high normal and elevated blood pressures are not under adequate medical supervision and are not being treated effectively. Certainly, those with high normal blood pressure should be trying to get back into the normal or optimal ranges by weight loss, exercise, and, if needed, by reducing dietary sodium. A diet high in fruits, vegetables, low fat dairy foods, poultry, fish, and nuts may also help reduce the blood pressure.

How often should we screen? For those with high normal pressures, there is no question; it should be annually. For those with normal blood pressure or even optimal blood pressure, a significant percentage will develop hypertension, moving first either from optimal to normal and then to high normal, or from normal to high normal. Healthful Life believes the earlier that progression is detected, the easier it is to do something about it, especially because it frequently is related to weight gain. We, therefore, will continue to recommend an annual measurement of blood pressure by a health care provider and frequent regular measurement of weight (at least monthly, preferably at least weekly).

Vasan, R.S., et al. Assessment of frequency of progression to hypertension in non-hypertensive participants in the Framingham Heart Study. The Lancet. Vol 358 (November 17) Pgs 1682-1686. 2001.

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