Chest
Volume 147, Issue 6, June 2015, Pages 1582-1590
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Original Research: Asthma
Effects of Weight Loss on Airway Responsiveness in Obese Adults With Asthma: Does Weight Loss Lead to Reversibility of Asthma?

https://doi.org/10.1378/chest.14-3105Get rights and content

BACKGROUND

The growing epidemics of obesity and asthma are major public health concerns. Although asthma-obesity links are widely studied, the effects of weight loss on asthma severity measured by airway hyperresponsiveness (AHR) have received limited attention. The main study objective was to examine whether weight reduction reduces asthma severity in obese adults with asthma.

METHODS

In a prospective, controlled, parallel-group study, we followed 22 obese participants with asthma aged 18 to 75 years with a BMI ≥ 32.5 kg/m2 and AHR (provocative concentration of methacholine causing a 20' fall in FEV1 [PC20] < 16 mg/mL). Sixteen participants followed a behavioral weight reduction program for 3 months, and six served as control subjects. The primary outcome was change in AHR over 3 months. Changes in lung function, asthma control, and quality of life were secondary outcomes.

RESULTS

At study entry, participant mean ± SD age was 44 ± 9 years, 95' were women, and mean BMI was 45.7 ± 9.2 kg/m2. After 3 months, mean weight loss was 16.5 ± 9.9 kg in the intervention group, and the control group had a mean weight gain of 0.6 ± 2.6 kg. There were significant improvements in PC20 (P = .009), FEV1 (P = .009), FVC (P = .010), asthma control (P < .001), and asthma quality of life (P = .003) in the intervention group, but these parameters remained unchanged in the control group. Physical activity levels also increased significantly in the intervention group but not in the control group.

CONCLUSIONS

Weight loss in obese adults with asthma can improve asthma severity, AHR, asthma control, lung function, and quality of life. These findings support the need to actively pursue healthy weight-loss measures in this population.

Section snippets

Study Design

In this 3-month prospective, controlled, parallel-group study in obese participants with physiologically proven asthma, we compared intervention participants who followed a low-calorie diet for the first 3 months of a 12-month behavioral weight reduction program to control participants who engaged in no specific weight management strategy while waiting for bariatric surgery. The study was approved by the Ottawa Health Science Network Research Ethics Board (2009847-01H).

Setting

The Weight Management

Results

Figure 1 presents the study flow. A total of 142 potentially eligible participants expressed interest in the study. Fifty-five (38.7') refused to participate following contact with the research team, and 25 (17.6') were excluded from the study. Sixty-two (43.7') signed a consent form and completed a baseline questionnaire. Forty-four subsequently completed an MCT, 22 of whom had positive results that confirmed their asthma diagnosis and eligibility to be part of the prospective 3-month

Discussion

This study demonstrated that a behavioral weight reduction program is associated with significant improvements in PC20, FEV1, FVC, asthma control, and quality of life in obese people with physiologically proven asthma. There was no change in any of these asthma outcomes in control participants who followed no weight-loss strategy. The results support findings of previous research that relate weight loss to improved lung function, asthma control, and quality of life10, 15, 18, 19, 20, 21 and add

Conclusions

This study suggests that weight loss in obese adults with asthma leads to significant improvements in asthma severity measured by AHR, resulting in normalization or improvements in AHR to methacholine (PC20), lung function, asthma control, and quality of life. These findings support the need to actively pursue healthy weight-loss measures in obese adults with asthma.

Acknowledgments

Author contributions: S. P. 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 analysis. S. P., R. D., K. V., and S. D. A. contributed to the study concept and design; S. P., J. B., R. D., and S. D. A. contributed to the data analysis and interpretation; and S. P., J. B., R. D., K. V., and S. D. A. contributed to the drafting, critical revision for important intellectual content, and final approval of the manuscript.

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    FUNDING/SUPPORT: Funding for this study was provided by the Department of Medicine, The Ottawa Hospital, and the Ontario Thoracic Society.

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.

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