[Association of BMI with acute exacerbation in mild to moderate chronic obstructive pulmonary disease patients in community: a prospective study]

Objective: BMI may play a protective role in reducing the mortality rate of patients with chronic obstructive pulmonary disease (COPD), but its effect on acute exacerbation of COPD remain unclear. Methods: Subjects were selected from the COPD patients registration system established in 2014 in Pudong new district, Shanghai. COPD patients from 8 communities were selected by cluster sampling and follow up was conducted prospectively for 18 months. Basic information and BMI were obtained from baseline survey, and acute exacerbations were collected during follow-up. The association between BMI and risk of acute exacerbation was evaluated by using multiple negative binomial regression. Results: Among 328 community COPD patients, 295 who completed the follow up were included in the analysis, in whom 96.3% (284/295) were mild COPD patients. During the follow-up, 11.1% (33/295) of the patients reported acute exacerbation. The results of multiple negative binomial regression suggested that, the risk for acute exacerbation decreased with the increase of BMI (IRR=0.85, 95%CI:0.73-0.98), overweight patients with BMI ≥25.0 kg/m² (IRR=0.36, 95%CI:0.13-0.91) or moderate BMI (T₂ vs. T₁, IRR=0.31, 95%CI:0.11-0.77) had lower risk for acute exacerbation compared with the patients with normal or low BMI. BMI had a linear correlation with the risk of acute exacerbation. Conclusion: The risk for acute exacerbation in patients with mild or moderate COPD in communities decreased with the increase of BMI, and being overweight might be a protective factor for the acute exacerbation of COPD.