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Nonlinear Relationship Between Body Mass Index Z-Scores and Lung Function Parameters in Asthmatic Children: A
Jing Wang1,2, Jinmao Gao3, Yuling Han1,2
1Department of Respiratory, Jinan Children's Hospital, Jinan, People's Republic of China.
Insights
Body mass index (BMI) in children with asthma shows a complex relationship with lung function. High BMI z-scores above a certain threshold can negatively impact lung function, suggesting weight-guided interventions are crucial for asthma management.
Area of Science:
- Pediatric Pulmonology
- Asthma Research
- Obesity and Health
Background:
- Asthma is a chronic respiratory condition affecting children worldwide.
- Body Mass Index (BMI) and its standardized measure, BMI z-scores, are increasingly recognized as factors influencing asthma severity and management.
- Understanding the precise relationship between weight status and lung function is critical for effective pediatric asthma care.
Purpose of the Study:
- To investigate the association between Body Mass Index (BMI) and BMI z-scores and various lung function parameters in children diagnosed with asthma.
- To identify potential threshold effects in the relationship between BMI z-scores and pulmonary function.
- To provide evidence for developing individualized treatment and management strategies for pediatric asthma patients.
Main Methods:
- A cohort of 328 children experiencing acute asthma exacerbations was studied.
- Lung function parameters including VCmax, FVC, FEV1, PEF, MMEF, MEF25, MEF50, and MEF75 were measured.
- Linear and piecewise regression models were employed to analyze the associations between BMI, BMI z-scores, and lung function, controlling for relevant covariates.
Main Results:
- Positive linear correlations were observed between BMI and several lung function measures (VCmax, FVC, FEV1, MEF50, MEF75, MMEF).
- BMI z-scores also showed positive linear associations with VCmax, FVC, FEV1, MEF25, MEF50, and MMEF, even after adjusting for confounders.
- Piecewise regression revealed a significant nonlinear relationship, with lung function declining in children with BMI z-scores exceeding approximately 2.3-3.9.
Conclusions:
- A nonlinear association exists between BMI z-scores and lung function parameters in children with asthma.
- Pulmonary function deteriorates significantly in children with asthma and elevated BMI z-scores beyond a specific threshold.
- Weight-guided interventions hold promise for improving lung function and overall asthma control in pediatric populations.
Introduction:
To assess the relationship between body mass index (BMI) and BMI z-scores with lung function parameters in children with asthma, aiming to provide scientific evidence for individualized treatment and management strategies.
Methods:
We enrolled 328 children with asthma during acute exacerbation. The BMI and BMI z-scores were analyzed in relation to lung function parameters, including maximum vital capacity (VCmax), forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), peak expiratory flow (PEF), maximal mid-expiratory flow rate (MMEF), and instantaneous flows at 25%, 50%, and 75% of maximal expiratory flow (MEF25, MEF50, MEF75). Both linear regression and piecewise regression models were used to identify linear associations and potential threshold effects.
Results:
BMI showed significant positive linear correlations with VCmax, FVC, FEV1, MEF50, MEF75, and MMEF, while BMI z-scores demonstrated positive linear associations with VCmax, FVC, FEV1, MEF25, MEF50, and MMEF. After adjusting for age, sex, immunoglobulin E (IgE), eosinophil count (EOS), fractional exhaled nitric oxide (FeNO), and asthma severity, both BMI and BMI z-scores remained positively associated with VCmax, FVC, and FEV1. Piecewise regression analysis revealed significant threshold effects in the relationships between BMI z-scores and VCmax, FVC, FEV1, PEF, MEF25, MEF50, MEF75, and MMEF. Below a z-score of ~2.3-3.9, BMI z-score was positively associated with pulmonary function. Above this threshold, the association reversed; for instance, FEV1 decreased by 9.7% (β = -9.69, 95% CI: -18.93 to -0.46) and PEF decreased by 12.2% (β = -12.17, 95% CI: -21.12 to -3.22) for every unit increase in BMI z-score beyond 3.945.
Conclusion:
A nonlinear relationship exists between BMI z-scores and lung function parameters in children with asthma. Weight-guided interventions may enhance lung function and asthma control.
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