<qa>  What is the study that compares the endpoints with?This is a 3 year longitudinal study to identify novel endpoints and compare these with standard measures such as forced expiratory volume in 1 second FEV1 for their ability to measure and predict COPD Chronic Obstructive Pulmonary Disease severity and its progression over time. Control subjects smokers and never smokers will be recruited as comparators with the COPD subjects. 