Pulse Pressure and Mortality

[Guest guest]

Hi folks:

Not all papers on this issue are in agreement (what is new!). But

here are a couple of interesting articles.

" Pulse Pressure and Mortality in Older People "

J. Glynn, ScD; U. Chae, MD; Jack M. Guralnik, MD, PhD;

O. , MD; H. Hennekens, MD, DrPH

Arch Intern Med. 2000;160:2765-2772.

" Background In older people, observational data are unclear

concerning the relationships of systolic and diastolic blood pressure

with cardiovascular and total mortality. We examined which

combinations of systolic, diastolic, pulse, and mean arterial

pressure best predict total and cardiovascular mortality in older

adults.

Methods In 1981, the National Institute on Aging initiated its

population-based Established Populations for Epidemiologic Studies of

the Elderly in 3 communities. At baseline, 9431 participants, aged 65

to 102 years, had blood pressure measurements, along with measures of

medical history, use of medications, disability, and physical

function. During an average follow-up of 10.6 years among survivors,

4528 participants died, 2304 of cardiovascular causes.

Results In age- and sex-adjusted survival analyses, the lowest

overall death rate occurred among those with systolic pressure less

than 130 mm Hg and diastolic pressure 80 to 89 mm Hg; relative to

this group, the highest death rate occurred in those with systolic

pressure of 160 mm Hg or more and diastolic pressure less than 70 mm

Hg (relative risk, 1.90; 95% confidence interval, 1.47-2.46). Both

low diastolic pressure and elevated systolic pressure independently

predicted increases in cardiovascular (P<.001) and total (P<.001)

mortality. Pulse pressure correlated strongly with systolic pressure

(R = 0.82) but was a slightly stronger predictor of both

cardiovascular and total mortality. In a model containing pulse

pressure and other potentially confounding variables, diastolic

pressure (P = .88) and mean arterial pressure (P = .11) had no

significant association with mortality.

Conclusions Pulse pressure appears to be the best single measure of

blood pressure in predicting mortality in older people and helps

explain apparently discrepant results for low diastolic blood

pressure. "

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And in a comment on another paper the following is clearly stated

(but is it correct?!):

" How Important Is Pulse Pressure as a Predictor of Cardiovascular

Risk? "

Stanley S. lin; D. Wong

Preventive Cardiology Program, University of California, Irvine,

California

G. Larson; B. Kannel; Levy

Framingham Heart Study, National Heart, Lung and Blood Institute,

Framingham, Massachusetts

To the Editor:

" Miura and colleagues1 report that pulse pressure (PP) is of no added

value to systolic blood pressure (SBP) in assessing long-term

cardiovascular (CV) mortality in 60- to 74-year-old men and women

volunteers from 84 cooperating Chicago-area companies and

organizations.

In contrast, we published a Framingham Heart Study report that found

coronary heart disease (CHD) risk in middle-aged and older

individuals to be inversely related to diastolic blood pressure (DBP)

at any given level of SBP 130 mm Hg (lin et al, 1999, Table 4),2

suggesting that PP may be superior to SBP as a predictor of risk in

this older population. We would like to consider some of the

explanations for the different results reported in our paper and that

of Miura et al.

First, numerous longitudinal and cross-sectional studies of age-

related changes in blood pressure have shown that mean DBP levels off

by about age 50 years and begins to decrease by the age of 60 years.3–

5 Contrary to these findings, the Miura study shows a rise in DBP

from age 40 to 59 versus age 60 to 74 in men (83.5 versus 85.8 mm Hg)

and in women (79.5 versus 82.3 mm Hg), suggesting that the Chicago-

area volunteer workers population may not be typical of many other

populations in the United States and around the world.

Second, Miura et al state correctly that the proper approach in

assessing the value of PP is to place both SBP and DBP in the same

model, and only if DBP has an inverse relation to CV mortality

can PP be shown superior to SBP. This inverse relation of DBP to CV

mortality was not observed in their study, largely because DBP

increased rather than decreased after age 60. In contrast, the

Framingham report,2 the Physicians Health Study,6 and the Medical

Research Council mild hypertension trial7 all showed an inverse

relation of DBP to CHD risk. Furthermore, there are 4 additional

publications, including a total of 11 different population databases,

that showed an inverse relation of DBP to total and CV mortality,8–11

strongly suggesting that PP is superior to SBP in predicting risk in

these elderly cohorts.

Thus, it would appear that not all elderly populations show the same

relation of PP in predicting cardiovascular disease. The reasons for

discrepancies between the Miura study and the majority of other

studies in this age group are not entirely clear. The presence of a

healthy cohort effect in the Miura study could well be the most

important factor, especially because the oldest group (ages 60 to 74)

had only a mean age of 63 years. The use of supine blood pressures in

the Miura study instead of the more conventional sitting position

also may have influenced results. Single blood pressure recordings in

the Miura study (verses 2 in the Framingham study) undoubtedly

reduced precision.

We also would like to correct the record on a few minor points made

by Miura et al. They reported that 2 studies, both from Framingham,

compared PP and SBP as predictors of CHD risk (Kannel, 2000, and

lin et al, 1999)2,12 and stated that these 2 studies came to

opposite conclusions. This is incorrect. Only lin et al, 1999,2

placed DBP and SBP in the same model to assess PP. Kannel,

2000,12 was a historical review article that compared SBP and DBP

separately as predictors of CHD risk and, therefore, did not come to

different conclusions from lin et al, 1999.2

Miura et al did show that DBP was superior to both PP and SBP in

predicting CV risk, but only in middle-aged men. Indeed, our recent

Framingham publication13 further clarified this issue by showing

superiority of DBP to PP and SBP in both young men and women. This

study showed that, with increasing age, there was a gradual shift

from DBP to SBP and then to PP as predictors of CHD risk. In patients

<50 years of age, DBP was the strongest predictor. The age-period 50

to 59 years was a transition period when all 3 blood pressure indices

were comparable predictors, and from 60 years of age on, DBP was

negatively related to CHD risk so that PP became superior to SBP.

These findings were largely confirmed by a British study using 24-

hour intra-arterial ambulatory blood pressure monitoring.11

Finally, we also agree with the authors that PP cannot replace SBP as

a single measure of cardiovascular risk. Indeed, of the 3 blood

pressure indices, SBP is the best predictor for the majority of

persons with hypertension. However, for older persons, the best

clinical strategy for estimation of cardiovascular risk is to first

determine the level of SBP elevation and then adjust the overall risk

upward if there is wide PP, ie, discordantly low DBP. "

------------------------------

To which the following was a reply:

Response:

Philip Greenland; Alan R. Dyer; Stamler

Department of Preventive Medicine, Northwestern University Medical

School, Chicago, Illinois

Katsuyuki Miura

Department of Public Health, Kanazawa Medical University, Ishikawa,

Japan

" We appreciate the interest of lin et al in our report1 on pulse

pressure compared with other blood pressure indices, each considered

singly, in predicting 25-year mortality from a large employed

population of men and women in Chicago. As we pointed out in our

paper,1 main findings from our study on coronary heart disease (CHD),

cardiovascular disease (CVD), and all-cause mortality were that (1)

relations of pulse pressure (PP) were less strong than were those of

systolic blood pressure (SBP) for all end points in all age/gender

groups studied; (2) relations of PP were less strong than were those

of diastolic blood pressure (DBP) for all end points in middle-aged

men and women and in older women; (3) among the 4 blood pressure (BP)

indices we studied, the strongest relation was observed for either

SBP or mean arterial pressure (MAP) in all age/gender groups; (4)

relations of SBP to death tended to be stronger than or similar to

those of DBP; and (5) with control for SBP, DBP was positively and

significantly related to death in middle-age men and women, but not

in younger men and older men and women. Thus, the major comments of

lin et al were previously discussed in our paper.

In addition, we acknowledged that our results were based on a single

measurement of BP. However, as we discussed, the consequence of this

is that our results probably are underestimates of true associations

because of regression dilution bias.2 We also recognized, and

discussed, the possible role of the " healthy worker effect. " As we

noted, however, it is a reasonable inference that our findings are

generalizable to other " healthy " general population samples.1 We also

discussed the age range in our study and noted previous reports

emphasizing the possibility, remaining to be confirmed, that PP

becomes more important physiologically and prognostically primarily

(or exclusively) at ages 60 years.3 Given that most of our oldest

participants were in their early 60s at entry, our findings may have

limited implications for persons beyond the age of 63 years, as we

also stated.1

Nothing in our results, or those reviewed by lin et al, suggests

that pulse pressure can replace an emphasis on SBP in older people,

healthy or otherwise. DBP may take precedence over SBP in risk

assessment in persons under age 60, but our results were not strong

in favor of this approach. As pointed out in our paper and by

lin et al, we did not confirm the results of lin et al as

to the added value of PP after age 60. As we previously stated, for

younger and middle-aged persons, the evidence is clear that an

emphasis on PP should be avoided. There is no evidence, in a general

population younger than age 60, that PP is superior to SBP in the

prediction of CVD or all-cause mortality. Detection and evaluation of

hypertension based mainly on SBP, considered together with DBP, per

the sixth report of the Joint National Committee of Prevention,

Detection, Evaluation, and Treatment of High Blood Pressure (JNC-VI)

recommendations,4 should remain the most practical and easy approach

in the general population for young adult, middle-aged, and older men

and women (at least up to about age 60 years). PP may have added

value in risk assessment, but, if so, apparently only in certain age

groups or in certain populations. "

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I am hoping to get my pulse pressure down to 35. It is currently ~41.

Any suggestions for ways to raise DBP without raising SBP?

Rodney.