Chronic bronchitis is an independently associated factor for more symptom and high-risk groups

BACKGROUND The chronic bronchitis (CB) phenotype has been associated with poor quality of life and an increased risk of disease in patients with COPD. However, little information exists regarding the relationship between the CB phenotype and the COPD assessment test (CAT) score. The goal of this study was to reveal the different pattern of CAT scores between CB and non-CB patients. Moreover, we aimed to investigate whether the CB phenotype is an independently associated factor for more symptom and high-risk groups. METHODS Data were obtained from the Korea COPD Subgroup Study cohort recruited from 46 centers in South Korea since April 2012. CB patients were defined as having a chronic cough and sputum for 3 months per year, for a period of 2 consecutive years. We investigated the pattern of CAT and subquestionnaire scores between CB and non-CB patients. We also analyzed the proportion of CB phenotypes in each Global initiative for chronic Obstructive Lung Disease (GOLD) stage. Finally, we performed a logistic regression analysis to identify whether the CB phenotype was an independently associated factor for more symptom and high-risk groups. RESULTS Of the 1,106 study patients, 11.5% of patients were found to have a CB phenotype. CB phenotypes were most common in GOLD III (GOLD 2006) and GOLD D (GOLD 2015) stages. CAT scores were significantly higher in CB patients not only in terms of the total score but also for each subquestionnaire. Logistic regression revealed that the CB phenotype is an independently associated factor for more symptom and high-risk groups. CONCLUSION The present study revealed that CB patients have higher CAT scores and subquestionnaire results compared to non-CB patients. Additionally, we demonstrated that the CB phenotype is an independently associated factor for both more symptom and high-risk groups.