Primary Outcome Measures:
- Change from baseline in post-bronchodilator forced expiratory volume in 1 second (FEV1) [ Time Frame: baseline, then at annual visits for up to 6 years ]
FEV1 is measured by having the participant inhale a dose of bronchodilator (albuterol/salbutamol), wait 15 minutes, and then inhale maximally and exhale maximally and forcefully into a spirometer. Participants do at least 3 trials of spirometry for each measurement, and up to 8, to obtain 3 usable measurements.
Secondary Outcome Measures:
- Change from baseline in respiratory health status using the St. George's Respiratory Questionnaire for COPD (SGRQ-C) [ Time Frame: baseline, then at annual visits for up to 6 years ]
The SGRQ-C is a standardized, validated, self-administered questionnaire that measures respiratory health status and includes domains of respiratory symptoms, activity limitations, and psychosocial impact. It will be given to participants to complete in their native language. It contains 40 items and takes approximately 10-15 minutes to complete.