Most of us are familiar with the “breathing tests” that asthmatics and emphysema patients take to see how their disease is fairing either during a flare up or routine monitoring of the their medications–inhalers and such. Yet if you don’t; have any lung disease, you are unlikely ever to have taken such a test.
Spirometry, as the breathing test is called, turns out to be an interesting biomarker of aging hiding in the clothing of pulmonary specialist’s test. While it certainly functions as a screen for early lung disease in undiagnosed asthmatics and smokers, it also measures the lung age of healthy individuals. In fact, in order to determine if the result of a spirometry test is abnormal, it must be compared to a large database of normal results adjusted for height, gender, ethnicity, and age. Spirometry performed by tens of thousands of individuals has resulted in large databases which can be used to determine lung age.
The complete testing session takes about 10 minutes. The patient takes as deep a breath as possible, places the airflow meter (pneumotach) in his mouth, then blows out the air as fast as possible in the first second. He then continues to blow for at least 5 seconds longer in an effort to completely empty his lungs. The computer attached to the pneumotach calculates the total amount of air expelled during the full exhalation, and the amount expelled in the first second. These measures are called the forced vital capacity (FVC), and the forced expiratory volume in the first second (FEV1), respectively. The procedure is repeated until 3 consistent measures are recorded.
Many large studies, including those that tracked people over long periods, have shown that both the FVC and FEV1 decline with age, and that there is a correlation between these biomarkers and mortality from all causes. One investigation, the Buffalo Health Study, followed nearly 1,200 men and women between the ages of 20 and 89 for twenty-seven years, with each subject being tested with spirometry every five years. It found that the lower the person’s percent of predicted FEV1, the greater the chances that he or she would not be alive the next time test time came around.
While spirometry results can be predictive of mortality risk, the correlation is not, as you might presume, between respiratory function and death caused by respiratory disease. This is where the picture becomes a bit ambiguous, and where it parts company with other biomarkers of aging. Arterial stiffness, for instance, correlates directly with life-threatening cardiovascular disease. But while the average person&rsquos FEV1 can be expected to decline about one percent a year–and that can add up to a significant percentage of functional loss over the course of a lifetime–such normal lung aging is not going to cause early death in most people. The more significant association is between lower spirometry readings and increased mortality of all kinds. These findings bolster the idea that respiratory function over time reflects how well the body as a whole is aging, making spirometry one of the most valuable biomarkers of aging. As Dr. Milton Hollenberg, of the University of California, San Francisco Medical Center puts it, “. . . we consider FEV1 as a surrogate for a number of unmeasured aging processes . . . and not as a specific measure of lung function.”
Taking an initial, or baseline test and then repeating it yearly, is an effective way to see how well your anti-aging program is working. If from year to year, there is no significant change, then your program is working. In addition, a baseline test can tell you if you are at significant increased risk for lung disease and often motivate smokers to quit.
