Chest

Chest

Volume 151, Issue 1, January 2017, Pages 68-77
Journal home page for Chest

Original Research: COPD
Obesity Is Associated With Increased Morbidity in Moderate to Severe COPD

These data have been presented at the 2015 American Thoracic Society International Conference, May 20, 2015, Denver, CO.
https://doi.org/10.1016/j.chest.2016.08.1432Get rights and content

Background

Obesity is prevalent in the United States; however, the impact of obesity on COPD morbidity is unclear. We hypothesized that obesity is associated with worse outcomes in COPD.

Methods

We examined 3,631 participants from the multicenter prospective cohort study Genetic Epidemiology of COPD (COPDGene) who had spirometry-confirmed COPD, a postbronchodilator FEV1 < 80% predicted, and a BMI ≥ 18.5 kg/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 range, 18.5-29.9 kg/m2).

Results

Overall, 35% of participants were obese, with 21% class I (BMI range, 30-34.9 kg/m2), 9% class II (BMI range, 35-39.9 kg/m2), and 5% class III (BMI ≥ 40 kg/m2). The number of comorbidities increased with increasing obesity class (P < .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 version 2, respectively), reduced 6-min walk distance (6MWD), increased dyspnea (Modified Medical Research Council score ≥ 2), and greater odds of 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.

Conclusions

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.

Section snippets

Study Population

The COPDGene study details have been reported.30 Briefly, the COPDGene study is a multicenter observational study including current and former smokers designed to identify genetic factors associated with COPD. Between January 2008 and April 2011, 10,192 non-Hispanic White (NHW) and black adults aged 45 to 80 years of age with a minimum 10 pack-year smoking history were enrolled. Participants were phenotyped by completing questionnaires, blood tests, imaging, and spirometry measurements. This

Participant Characteristics

Demographic and clinical characteristics are presented in Table 1, stratified by obesity class. Overall, 34% of participants were obese, with 21% in class I, 9% in class II, and 5% in class III. Age, sex, race, education, and smoking pack-years were similar across weight categories. Active tobacco use (current smoking) was most prevalent among the normal/overweight individuals (43%) and those with class III obesity (40%). Absolute and percent predicted FEV1, and the FEV1 to FVC ratio, were

Discussion

In this large, well-characterized cohort of individuals with COPD and GOLD stages 2 through 4 severity of airflow obstruction, obesity was prevalent, affecting approximately one-third of the population. Increasing severity of obesity was associated with worse COPD morbidity. We show that obesity is not only linked to subjective outcomes, such as worse QOL and dyspnea, but also to increased risk of severe AECOPD. The link between obesity and exacerbations may be partly explained by increased

Conclusions

Comorbid obesity and COPD is prevalent, and increasing obesity is associated with increased comorbidity, reduced QOL, impaired functional status, and increased risk for severe AECOPD. Importantly, even class I obesity adversely impacted COPD outcomes, with increasing severity of obesity associated with greater magnitude of deficits in a dose-dependent fashion. Patients with COPD should be assessed for comorbid obesity and closely monitored for COPD outcomes. Determination of the impact of

Acknowledgments

Author contributions: A. A. L. had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. A. A. L., N. P., M. C. M., and N. N. H. contributed to the analysis plan, interpretation, and writing and editing of the report. M. B. D., A. M. B., N. A. H., V. K., G. L. K., M.-L. N. M., E. P. B., and R. A. W. contributed to the data interpretation and writing and editing of the report.

Financial/nonfinancial disclosures:

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    • Cited by (0)

    FUNDING/SUPPORT: This study was funded by the National Institutes of Health Genetic Epidemiology of COPD [Grant R01 HL089856] to Dr Silverman (PI) and [Grant R01 HL089897] to Dr Crapo (PI); the National Institutes of Health [Grant KL2 TR001077] to A. A. L., [Grant K23 HL123594] to N. P., [Grant K23 HL094696] to V. K., [Grants P50MD010431 and R01ES022607] to N. N. H. and M. C. M., and [Grant R01ES023500] to N. N. H.; the National Institutes of Health, National Heart, Lung, and Blood Institute [Grant 1K99HL121087-01A1] to M.-L. N. M.; the National Institutes of Health, National Center for Advancing Translational Sciences [Grant 4KL2TR001077-04] to E. P. B.; and the Environmental Protection Agency [Grant RD-83615001] to N. N. H. and M. C. M.

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    Copyright © 2016 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.