Asthma Control Measures Are Not Associated with Decreased Lung Function in Obese Children with Severe Asthma

Abstract

Asthma and obesity are two of the most common health problems in children in the United States. A growing cohort of literature is attempting to better describe the complex relationship between the two. Obtaining a better understanding of the clinical phenotypes associated with abnormal weight status and severe asthma may help to provide targeted care to this unique patient population Methods: We performed a retrospective chart review of asthmatic patients seen in our outpatient clinic at a Tertiary Pediatric Hospital. Overweight and Obese children (BMI >85 th percentile; OW/Ob group) with asthma were compared to those with a normal BMI. Primary outcomes were spirometry results (pre-bronchodilator FVC, FEV1, FEV1/FVC, and FEF 25-75%). We also looked at the Asthma Control Test (ACT) and serum studies. Results: 269 children with asthma were included in this study. Roughly 43% were overweight or obese, 36.6% were female, 78.9% were African-American, 26.8% had severe persistent asthma and average age was 7.2 years. There were no significant differences in gender, ethnicity, or proportion of severe asthma between the normal BMI and OW/Ob groups. There was no difference in serum eosinophils, FeNO, IgE, courses of oral steroids or hospital admissions between normal BMI and OW/Ob groups, regardless of asthma severity. OW/Ob children with severe persistent asthma had higher serum neutrophil % on CBC (47% vs 40%; p-value 0.046). There was also no significant difference in measures of asthma control (ACT 16.6 vs. 16.9; p=0.81). Of the children with spirometry results (n=185), the OW/Ob group had a higher %predicted FVC (94.5 vs. 89.0, zscore +0.17; p-value =0.02 for both) and lower FEV1/FVC (79.37 vs 83.48 actual, z-score-0.20; p-value=0.008 for both). In children with severe persistent asthma, the OW/Ob group had lower FEV1/FVC (73.09 vs 82.28 actual, z-score-0.80; p-value=0.001 for both) and FEF25-75% predicted (49.3 vs 69.96; p-value=0.01; z-score not significant). Conclusion: Our study supports previous reports of airway dysanapsis in overweight and obese children with asthma. We identified significantly lower FEV1/FVC and FEF25-75% in overweight/obese children with asthma, particularly those with severe asthma, despite no differences in validated (ACT) and traditional measures (admission/oral steroid rates) of asthma control. These results do not seem to be TH2 driven, as eosinophils, FeNO, and IgE are similar in both groups.