https://orcid.org/0000-0001-8933-387X
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Abstract
Purpose
To analyze the relationship between body mass index (BMI) and lung function, which may help optimize the screening and management process for chronic obstructive pulmonary disease (COPD) in the early stages.
Patients and Methods
In this cross-sectional study using data from the Enjoying Breathing Program in China, participants were divided into two groups according to COPD Screening Questionnaire (COPD-SQ) scores (at risk and not at risk of COPD) and three groups based on lung function (normal lung function, preserved ratio impaired spirometry [PRISm], and obstructive lung function).
Results
A total of 32,033 subjects were enrolled in the current analysis. First, in people at risk of COPD, overweight and obese participants had better forced expiratory volume in one second (FEV1; overweight: 0.33 liters (l), 95% confidence interval [CI]: 0.27 to 0.38; obesity: 0.31 L, 95% CI: 0.22 to 0.39) values than the normal BMI group. Second, among people with PRISm, underweight participants had a lower FEV1 (−0.56 L, 95% CI: −0.86 to −0.26) and forced vital capacity (FVC; −0.33 L, 95% CI: −0.55 to −0.11) than participants with a normal weight, and obese participants had a higher FEV1 (0.22 L, 95% CI: 0.02 to 0.42) and FVC (0.16 L, 95% CI: 0.02 to 0.30) than participants with a normal weight. Taking normal BMI as the reference group, lower FEV1 (−0.80 L, 95% CI: −0.97 to −0.63) and FVC (−0.53 L, 95% CI: −0.64 to −0.42) were found in underweight participants with obstructive spirometry, and better FEV1 (obesity: 0.26 L, 95% CI: 0.12 to 0.40) was found in obese participants with obstructive spirometry.
Conclusion
Being underweight and severely obese are associated with reduced lung function. Slight obesity was shown to be a protective factor for lung function in people at risk of COPD and those with PRISm.
Abbreviations
BMI, body mass index; COPD-SQ, the COPD Screening Questionnaire; COPD, Chronic Obstructive Pulmonary Disease; PRISm preserved ratio impaired spirometry; preFEV1, the predicted forced expiratory volume in one second; FEV1, the forced expiratory volume in one second; FVC, the forced vital capacity; preFVC, the predicted forced vital capacity; FEV1/FVC, the ratio of FEV1 to FVC; AUC, area under the curve; GOLD, Global Initiative for Chronic Obstructive Disease.
Data Sharing Statement
The Enjoying Breathing Program will last for 10 years and is not fully completed at present. Our present study is part of this project, and only focuses on the relationship between BMI and lung function among different characteristic participants. Thus, the data is not available to the public currently. If someone would like details about the data, they can contact the corresponding authors.
Ethics Approval and Informed Consent
This national clinical study was registered in March 2020 (Clinical Trials ID: NCT04318912). Ethical approval was granted by the China-Japan Friendship Hospital (approval number 2019-41-k29). This study was conducted in accordance with the ethical principles of the Declaration of Helsinki. All participants included in this study were informed about the study and signed the informed consent.
Author Contributions
All authors made a significant contribution to study design, execution, acquisition of data, analysis and interpretation of data; took part in drafting the article or revising it critically for important intellectual content; agreed to submit to the current journal; gave final approval of the version to be published; and agree to be accountable for all aspects of the work.
Disclosure
The authors report no conflicts of interest in this work.