### Description

Hansen et al used the actual to predict ratio of FEV1-to-FVC to estimate a smoker's lung age. Demonstrating a significant lung problem may be helpful for convincing a smoker to quit. The authors are from the University of California David Geffen School of Medicine.

Parameters:

(1) FEV1 in liters (volume of air expired in the first second.)

(2) FVC in liters

(3) age of the patient in years

actual %FEV1/FVC =

= (measured FEV1 in liters) / (measured FVC in liters)

predicted %FEV1/FVC =

= 98.8 - (0.25 * (age in years)) - (1.79 * (FVC))

where:

• The equation is for normal never smokers. The FVC for the equation probably should be the expected FVC for the stated age rather than that of the patient..

difference =

= (predicted ratio) - (actual ratio)

delta lung age =

= 3 * (difference)

apparent lung age =

= (current lung age) + (delta lung age)

An alternative approach might be to rearrange the prediction equation:

age in years =

= ((actual ratio) - 98.8 + (1.79 * (FVC))) / (-0.25) =

= 395.2 - (7.166 * (FVC)) - (4 * (actual ratio))