Women can gauge what their fitness level should be at a given age to reduce risk of death

[Guest guest]

Colleagues, the following is FYI and does not necessarily reflect my own

opinion. I have no further knowledge of the topic.

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Public release date: 3-Aug-2005

http://www.eurekalert.org/pub_releases/2005-08/nmh-wcg080105.php

Contact: Patty Keiler

pkeiler@...

Northwestern Memorial Hospital

Women can gauge what their fitness level should be at a given age to

reduce risk of death

Research reported in this week's NEJM for the first time looks at the

role of exercise capacity in predicting a woman's risk of mortality

Researchers have developed a nomogram (alignment chart) specifically for

women that can be used to predict their expected exercise capacity at

any given age, as well as demonstrated that the resulting measure is a

predictor of the risk of death. Women whose exercise capacity was less

than 85 percent the age-predicted value had twice the risk of death

compared to women reaching at least 85 percent. according to research

led by Martha Gulati, MD, a cardiologist at the Bluhm Cardiovascular

Institute of Northwestern Memorial Hospital, which will be published in

the August 4 issue of the New England Journal of Medicine.

" This is the first study of its kind in women, " said Dr. Gulati.

" Despite extensive research on the role of exercise stress testing and

exercise capacity, there has been a lack of data on what is normal or

expected for healthy women. Until now, they have been evaluated using

the men's nomogram, which does not provide an accurate assessment for

women. "

Exercise capacity can be estimated by performing a symptom-limited

stress test based on the speed and grade of the treadmill. It is defined

as the maximal oxygen uptake for a given workload and can be expressed

in metabolic equivalents (MET). MET is the amount of oxygen used by an

average seated person and increases with the intensity of exercise.

To utilize the nomogram to establish the percentage of predicted

exercise capacity for age requires only the woman's age and exercise

capacity achieved in MET on the exercise stress test. Drawing a straight

line between the age and exercise capacity will allow the determination

of the percentage of predicted exercise capacity for age; a value of 100

percent is the mean for any given age. Any result greater than 100

percent indicates better-than-average performance. Any result lower than

100 percent indicates some degree of functional impairment for age.

Use of the women's nomogram provides a more accurate assessment of

prognosis among women than does use of the men's nomogram. " Use of the

male nomogram to assess women results in a lower sensitivity,

translating into more false positives, " said Dr. Gulati. " That means a

woman might be told she's at a higher risk for death when, in fact,

she's not. " The sensitivity and specificity of the survival model for

predicting death from any cause among the asymptomatic women are 70

percent and 47 percent, respectively, when the women's nomogram is used.

In contrast, the sensitivity and specificity are 55 and 64 percent,

respectively, when the men's nomogram is used.

" As age increases, so does the difference in predicted exercise capacity

between men and women, " explains Dr. Gulati. " Use of the men's nomogram

in this study group would have resulted in 800 more false positive

results, " adds Dr. Gulati.

For this study, 5,721 asymptomatic women and 4,471 symptomatic women

underwent a symptom-limited treadmill test according to the Bruce

protocol, the most commonly performed stress test. The nomogram was then

used to determine the percentage of predicted exercise capacity for both

cohorts. Survival data were obtained and a survival analysis was used to

estimate the rates of death from any cause and cardiac causes in each group.

The relationship between exercise capacity and the risk of death from

cardiac cause was remarkably similar for all age groups in the

symptomatic cohort, with two exceptions. The youngest (less than 55

years of age) and oldest women (older than 70 years) with a poor

exercise capacity had an especially high mortality rate.

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