Obesity is prevalent in the United States; however the impact of obesity upon COPD morbidity is unclear. We hypothesized that obesity is associated with worse outcomes in COPD.
We examined 3631 participants from the multicenter prospective cohort study COPDGene who had spirometry confirmed COPD, a post-bronchodilator FEV1 <80% predicted and a body mass index (BMI) ≥18.5kg/m2. We conducted logistic and linear regression analyses to determine the association between COPD outcomes and obesity class, adjusting for relevant confounders. The referent for obesity classes included normal/overweight individuals (BMI 18.5-29.9kg/m2).
Overall, 35% of participants were obese, with 21% class I (BMI 30-34.9kg/m2), 9% class II (BMI 35-39.9kg/m2) and 5% class III (BMI ≥ 40kg/m2). The number of comorbidities increased with increasing obesity class (p<0.001). Increasing obesity class was independently associated with worse respiratory-specific and general quality of life (QOL; St. George’s Respiratory Questionnaire score and Short Form-36 score v2, respectively), reduced 6 minute walk distance (6MWD), increased dyspnea (modified Medical Research Council score of ≥2) and greater odds of a severe acute exacerbation of COPD (AECOPD). The associations between obesity and worse outcomes were independent of the presence of comorbidities, except in the case of SF-36 and severe exacerbations.
Obesity is prevalent among individuals with COPD and associated with worse COPD-related outcomes, ranging from QOL and dyspnea to 6MWD and severe AECOPD. These associations were strengthened when obesity was analyzed as a dose-dependent response. Obesity in patients with COPD may contribute to a worse COPD-related course.