Defining Chronic Mucus Hypersecretion Using the CAT in the SPIROMICS Cohort

Area of Science:

• Pulmonology
• Respiratory Medicine
• Clinical Trials

Background:

• Chronic obstructive pulmonary disease (COPD) frequently involves chronic cough and phlegm.
• Chronic mucus hypersecretion (CMH) is traditionally defined by symptom duration (≥3 months) or chronic bronchitis (CB) criteria.
• Existing definitions lack a simple, routine clinical assessment tool.

Purpose of the Study:

• To evaluate if the COPD Assessment Test (CAT) can identify chronic mucus hypersecretion (CMH) populations and outcomes.
• To compare CAT-based CMH identification with established Medical Research Council (MRC) and St. George's Respiratory Questionnaire (SGRQ) definitions.
• To assess the correlation between CMH definitions and exacerbation frequency in COPD patients.

Main Methods:

• Identified CMH in the SPIROMICS COPD cohort using MRC, SGRQ, and CAT definitions.
• Determined optimal cut-points for CAT cough and phlegm items.
• Analyzed exacerbation frequencies (moderate and severe) over 3 years, stratified by smoking status.

Main Results:

• 49% of participants had CAT-defined CMH, comparable to SGRQ-defined CMH (47%).
• An optimal CAT cut-point of ≥2 for cough and phlegm items identified CMH.
• CMH presence, regardless of definition, correlated with higher exacerbation frequencies over 3 years.

Conclusions:

• The CAT effectively identifies SGRQ-defined CMH, a significant COPD trait linked to exacerbations.
• CAT-based CMH identification offers a simple, valuable approach for clinical settings, telemedicine, and trials.
• The CAT provides a novel method for characterizing COPD patients in real-world and remote settings.