Obesity's effect on asthma extends to diagnostic criteria

Area of Science:

• Pulmonary Medicine
• Allergy and Immunology
• Clinical Research

Background:

• Inflammatory biomarkers are increasingly used to classify lung inflammation in asthma.
• The impact of obesity on these inflammatory markers in asthma is not well understood.

Purpose of the Study:

• To investigate the effect of obesity on conventional inflammatory biomarkers in asthma patients.
• To assess the predictive value of IgE, blood eosinophils, and FeNO for sputum eosinophilia in different weight groups.

Main Methods:

• Secondary analysis of 652 asthma patients from two clinical trials.
• Linear correlation and logistic regression analyses were used to evaluate biomarker relationships and predictive values.
• Cut points for biomarkers were determined to maximize sensitivity and specificity for predicting sputum eosinophilia.

Main Results:

• Weak correlations were observed among inflammatory markers overall.
• In obese asthmatic subjects, only IgE and blood eosinophil counts showed a significant correlation (r=0.33).
• Biomarkers poorly predicted sputum eosinophilia in obese subjects, with lower predictive cut points identified for IgE, FeNO, and blood eosinophils.

Conclusions:

• Conventional inflammatory biomarkers have poor predictive value for eosinophilic airway inflammation in obese asthmatic individuals.
• Current biomarkers for classifying eosinophilic inflammation should be used with caution in obese asthma patients.