14 September 2000

Lung Function May Predict Long Life Or Early Death

by Kate Melville

How well your lungs function may predict how long you live.

This finding is the result of a nearly 30-year follow-up of the association between impaired pulmonary function and all causes of mortality, conducted by researchers at the University at Buffalo.

Results of the study appear in the September issue of Chest.

The UB researchers found that the 20 percent of men with the poorest lung function when the study began were more than twice as likely to have died during follow-up than men with the best lung function. Women in the lowest group were more than 1 1/2 times more likely to have died.

"This observation suggests that those with lower lung function levels may need to pay particular attention to avoid negative effects, such as smoking, on their lungs," said Holger Schünemann, M.D., research assistant professor in the UB Department of Social and Preventive Medicine and led author on the study.

He also suggested that physicians conduct a simple lung function test as part of a routine physical examination.

Schünemann and colleagues analyzed data from the Buffalo Blood Pressure/Erie County Air Pollution-Pulmonary Function Study collected during 1960 and 1961. The original study enrolled 2,273 women and men between the ages of 15 and 96. Researchers collected information on lifestyle factors and health status, including pulmonary function. In 1990, a follow-up study determined which participants had died and their cause of death.

The purpose of the current study was to investigate the association between pulmonary function and mortality for periods that extended past 25 years, the limit of previous studies. Schünemann and colleagues also wanted to determine for how long pulmonary function is a significant predictor of mortality.

After excluding those with incomplete lung-function data and participants who were younger than 20 at baseline, Schünemann and colleagues ended up with 1,119 subjects -- 641 women and 554 men. They compared one measure of pulmonary function -- the volume of air exhaled in one second (forced expiratory volume or FEV1) -- with death records.

Results showed that lung function was a significant predictor of longevity in the whole group for the full 29 years of follow-up.

"It is important to note that the risk of death was increased for participants with moderately impaired lung function, not merely those in the lowest quintile," Schünemann said. "This suggests that the increased risk isn't confined to a small fraction of the population with severely impaired lung function."

The reasons lung function may predict mortality are not clear, Schünemann said, noting that increased risk is found in persons who never smoked, as well as among smokers.

"The lung is a primary defense organism against environmental toxins. It could be that impaired pulmonary function could lead to decreased tolerance against these toxins. Researchers also have speculated that decreased pulmonary function could underlie an increase in oxidative stress from free radicals, and we know that oxidative stress plays a role in the development of many diseases."

Schünemann said the fact that a relationship does exists between lung function and risk of death should motivate physicians to screen patients for pulmonary function, even if more research is needed to determine why.

"It is surprising that this simple measurement has not gained more importance as a general health assessment tool," he noted.