Lung function decline over 5 years in smokers with COPD in the lung health study

FEV₁ undergoes a one time change during the first year of follow up and then declines linearly. Patients who received ipratropium in addition to smoking intervention had a small increase in FEV₁ in the first year but then showed the same rate of decline as the others. This improvement in lung function with ipratropium was lost within a few weeks of stopping the medication at the end of the study (not shown).