This observational study aims to understand where and how airflow limitation happens in people with COPD, emphysema, and asthma-COPD overlap. Researchers are looking at people who are current or former smokers (over 15 pack years) and have mild to severe breathing problems. You might be eligible if you have asthma-COPD overlap, emphysema, or COPD/bronchitis with a history of smoking. The study will measure the site and mechanisms of expiratory airflow limitation over 4 years. This study is not testing new treatments, but rather observing how these conditions affect your lungs. The current status of this study is unclear.

Study design

This is an observational study planning to include 60 participants. It is not testing a specific treatment, but rather observing how certain lung conditions affect breathing.

What's involved

You would undergo extensive lung function testing, including spirometry (breathing tests) before and after using albuterol, lung volume measurements, and tests of lung elasticity. Blood tests and high-resolution CT scans of your lungs would also be performed.

Compensation

Not stated in the trial record.

Follow-up

The primary outcome, site and mechanism(s) of expiratory airflow limitation, will be measured at 4 years.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.