Oscillometry-defined Small Airway Dysfunction in Tobacco-exposed Adults with Impaired or Preserved Airflow

Area of Science:

• Pulmonary Medicine
• Respiratory Research
• Cardiovascular Health

Background:

• Small airway dysfunction (SAD) is a key feature of Chronic Obstructive Pulmonary Disease (COPD).
• SAD may be present in tobacco-exposed adults even with normal spirometry, but its role is understudied.
• Oscillometry is a valuable tool for detecting SAD.

Purpose of the Study:

• To determine the prevalence of oscillometry-defined SAD in tobacco-exposed adults.
• To explore associations between SAD and airway structural changes, quality of life (QoL), and metabolic and cardiovascular disease (CVD).
• To investigate SAD in individuals with both impaired and preserved airflow.

Main Methods:

• A sub-cohort of 1628 participants from a lung cancer screening trial was analyzed.
• Airway disease was assessed using spirometry, oscillometry, and AI-powered CT scans.
• SAD was defined by frequency dependence of resistance or reactance area; impaired airflow included airflow obstruction (AFO) and preserved ratio impaired spirometry (PRISm).

Main Results:

• Overall SAD prevalence was 39%, present in 26% with preserved airflow (PA-SAD) and 60% with impaired airflow.
• PA-SAD was associated with lower QoL, increased airway wall thickness, narrower lumen, fewer airway branches, and higher rates of metabolic and CVD compared to normal lung function.
• SAD, even in individuals with preserved airflow, was independently associated with CVD (OR: 1.91).

Conclusions:

• SAD is highly prevalent in tobacco-exposed adults and linked to adverse health outcomes, including structural lung changes, reduced QoL, and increased CVD risk, irrespective of spirometric classification.
• PA-SAD is a distinct entity from AFO, characterized by preserved airway count and minimal emphysema.
• Early detection and management of SAD are crucial for mitigating long-term respiratory and cardiovascular consequences.