The risk of acute exacerbations of chronic bronchitis is higher in non-obese patients with chronic bronchitis, according to a recent study reported in the journal Respiratory Research.¹

The participants for this study were recruited from the multicenter Korean COPD Subgroup Study (KOCOSS), with an objective to study the association between BMI and COPD exacerbations in patients with chronic bronchitis. They were categorized based on a BMI cut-off mark of 25 kg/m² into four groups: non-CB with BMI < 25 kg/m2, non-CB with BMI ≥ 25 kg/m2, CB with BMI < 25 kg/m² and CB with BMI ≥ 25 kg/m2. Exacerbations were compared across these four groups at follow-up after one year.

Out of the 1264 patients selected for the study, 451 (35.7%) had CB and 353 (~28%) had CB with BMI < 25 kg/m2.  Compared to the non-CB with BMI ≥ 25 kg/m2 group, the incidence rates were 1.21, 1.20 and 1.41, respectively among non-CB with BMI < 25 kg/m2, CB with BMI ≥ 25 kg/m2, and CB with BMI < 25 kg/m2 groups after adjusting for age, sex, smoking status, FEV1, use of inhaled steroids and history of exacerbation in the preceding year.

Compared with other groups, chronic bronchitis patients with BMI < 25 kg/m2 group complained of more dyspnea; they also had lower lung function and reported poor quality of life at the start of the study. These patients were at a greater risk of acute exacerbations.

This study has demonstrated an association between BMI and COPD. The risk of acute exacerbations of COPD was increased in patients with chronic bronchitis and BMI <25 delineated as the “non-obese phenotype of chronic bronchitis”. This group of patients had lower DLco (indicative of greater extent of emphysema) and more hyperinflation, factors which are associated with frequent exacerbations. According to the authors, these findings need to be validated and better defined. Also “more specific phenotype-driven approaches” are required for the management of non-obese patients with chronic bronchitis.

Reference

1. Sun Hye Shin, et al. Association of body mass index and COPD exacerbation among patients with chronic bronchitis. Respir Res. 2022 Mar 7;23(1):52. doi: 10.1186/s12931-022-01957-3.