Chronic Obstructive Pulmonary Disease (COPD) Clinical Trials

The goal of this observational study is to learn about the short- and long-term outcomes of people admitted to hospital with an acute respiratory condition, including exacerbations of chronic lung disease, and to understand factors that may predict recovery, hospital readmission, length of hospital stay, and mortality. A group of people with chronic respiratory disease who are being followed in respiratory outpatient clinics and a healthy control group without lung disease will also take part. The main questions it aims to answer are: * Which clinical, physical, functional, and biological characteristics are associated with short-term outcomes after hospitalisation, including 30-day hospital readmission, length of hospital stay, and 30-day mortality? * Which characteristics are associated with longer-term recovery, future exacerbations, hospital readmissions, healthcare use, and mortality? * Can measurements taken during or around the time of hospitalisation be used to identify people at greater risk of poor outcomes who may benefit from targeted interventions? Participants will undergo clinical assessments that may include questionnaires, measurements of physical function and muscle strength, lung function tests, physical activity monitoring, and collection of biological samples. Some participants may also undergo additional assessments of body composition, muscle size and function, imaging, or muscle metabolism, including through nested sub-studies. Participants will be followed for up to 36 months to assess recovery and longer-term clinical outcomes.