<p>Defining Chronic Mucus Hypersecretion Using the CAT in the SPIROMICS Cohort</p>

Abstract

Background: Chronic cough and phlegm are frequently reported chronic obstructive pulmonary disease (COPD) symptoms. Prior research classified chronic mucus hypersecretion (CMH) based on the presence of these symptoms for ≥3 months, called chronic bronchitis (CB) if respiratory infection symptoms were present for 1-2 years (Medical Research Council [MRC] definition). We explored whether the COPD Assessment Test (CAT), a simple measure developed for routine clinical use, captures CMH populations and outcomes similarly to MRC and St. George's Respiratory Questionnaire (SGRQ) definitions. Methods: We identified CMH in the SPIROMICS COPD cohort using (a) MRC definitions, (b) SGRQ questions for cough and phlegm (both as most/several days a week), and (c) CAT cough and phlegm questions. We determined optimal cut-points for CAT items and described exacerbation frequencies for different CMH definitions. Moderate exacerbations required a new prescription for antibiotics/oral corticosteroids or emergency department visit; severe exacerbations required hospitalization. Results were stratified by smoking status. Results: In a population of 1431 participants (57% male; mean FEV 1 % predicted 61%), 47% and 49% of evaluable participants had SGRQ-or CAT-defined CMH, respectively. A cut-point of ≥2 for cough and phlegm items defined CMH in CAT. Among SGRQ-CMH+ participants, 80% were also defined as CMH+ by the CAT. CMH+ participants were more likely to be current smokers. A higher exacerbation frequency was observed for presence of CMH+ versus CMH− in the year prior to baseline for all CMH definitions; this trend continued across 3 years of follow-up, regardless of smoking status. Conclusion: Items from the CAT identified SGRQ-defined CMH, a frequent COPD trait that correlated with exacerbation frequency. The CAT is a short, simple questionnaire and a potentially valuable tool for telemedicine or real-world trials. CAT-based CMH is a novel approach for identifying clinically important characteristics in COPD that can be ascertained in these settings.

Comparison of clinical characteristics between mild chronic bronchitis and severe chronic bronchitis in patients with chronic obstructive pulmonary disease

“…In a previous study, we showed that patients with CAT score-de ned CB shared clinical characteristics and outcomes with patients who had classically de ned CB [15]. While cut-off values have not been validated in other populations, a recent study based on Subpopulations and Intermediate Outcomes Measures in COPD Study (SPIROMICS) data suggested CAT1 and CAT2 cut-off scores of ≥ 2 [17]. Further studies are needed to validate a CAT score-based de nition of CB in other populations.…”

Comparison of clinical characteristics between chronic bronchitis and non-chronic bronchitis in patients with chronic obstructive pulmonary disease

“…The clinical significance of the CB phenotype in COPD is well-established. CB is associated with poor health-related quality of life [ 22 – 25 ], poor functional exercise capacity [ 26 ], low lung function [ 11 , 22 , 23 , 27 , 28 ], more frequent exacerbations [ 11 , 17 , 22 , 23 , 27 ], and higher mortality [ 24 , 29 ]. Consistent with those previous findings, our study showed higher mMRC and CAT scores, worse 6MWT performance, worse lung function, and more frequent exacerbations in CB patients than in non-CB patients.…”

“…However, there may be recall bias during long-term evaluations and the definitions of CB are complicated; thus, other parameters have been used in some studies, including chronic cough, physician diagnosis, and the presence of cough and sputum for 3 months over > 1 year [ 12 , 13 , 36 ]. Symptom-based scores (e.g., SGRQ and CAT) have also been employed [ 11 , 15 , 17 , 21 , 27 ]. Such scoring systems allow symptom severity to be quantified based on cut-off values, rather than subjective definitions.…”

“…In a previous study, we showed that patients with CAT score-defined CB shared clinical characteristics and outcomes with patients who had classically defined CB [ 15 ]. While cut-off values have not been validated in other populations, a recent study based on Subpopulations and Intermediate Outcomes Measures in COPD Study (SPIROMICS) data suggested CAT1 and CAT2 cut-off scores of ≥ 2 [ 17 ]. Further studies are needed to validate a CAT score-based definition of CB in other populations.…”

“…In 1978, the American Thoracic Society defined CB based on the presence of frequent cough and sputum production for 3 months per year over 2 consecutive years; however, there were some limitations using in both clinical and research field [ 15 , 16 ]. A recent approach to the assessment of CB is the use of sub-questionnaires from the COPD Assessment Test (CAT) [ 15 , 17 ]. In the eight sub-questionnaires, the scores range from 0 to 5 points [ 18 – 20 ].…”