Allergy and Airway: Asthma I |

Association of BMI With Airways Hyper-Responsive to Methacholine FREE TO VIEW

Karthik Vijayan, MD; Promish Shrestha, MD; Manuel Bautista, MD; Lawrence Goldstein, MD; Bhiputhi Neupane, MD
Author and Funding Information

Western Reserve Health Education, Youngstown, OH

Copyright 2016, American College of Chest Physicians. All Rights Reserved.

Chest. 2016;149(4_S):A13. doi:10.1016/j.chest.2016.02.015
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SESSION TYPE: Original Investigation Poster

PRESENTED ON: Saturday, April 16, 2016 at 11:45 AM - 12:45 PM

PURPOSE: Obesity increases the risk of asthma and contributes to a more difficult-to-control phenotype of the disease. In spite of the compelling evidence of association between asthma and obesity, relation between the BMI and increased airway/bronchial hyper-responsiveness (AHR/BHR) which is the basic physiological abnormality in asthma, has shown conflicting results. Provocative concentration of methacholine that reduces FEV1 by 20% (PC20) is a measure of AHR used in diagnosis of asthma. This study is aimed at exploring the relationship between BMI and PC20 in individuals suspected to have asthma, whose airways are hyper-responsive to methacholine.

METHODS: Retrospective case review of patients with cough, wheezing or dyspnea tested for bronchial hyper-responsiveness to methacholine in pulmonary lab. BMI Categorization (WHO classification) BMI (kg/m2) <18.5 -Underweight 18.5-24.9 -Normal weight 25-29.9 -Overweight ≥30 -Obesity Inclusion Criteria Patients with bronchial hyper-responsiveness (PC20 <16) to methacholine Exclusion Criteria Age<18 Patients with normal response (PC20>16) to methacholine Decrease in FEV1 >10% (form baseline) on a diluent (0.9% saline) Data analysis and interpretation (BMI-adjusted for age, pulmonary function and smoking) Spearman Rank Correlation between BMI and PC20 in males and females Kruskal-Wallis Test between the categories of BMI and median PC20

RESULTS: 135 of 358 tested patients had bronchial hyper-responsiveness (PC20 <16) to methacholine. Spearman Rank Correlation between BMI and PC20 in males and females Male (n=47) -.201 p=.1760 Female (n=88) -.065 p=.5449 Total (n=135) -.098 p=.2591 No significant correlation Kruskal-Wallis Test between the categories of BMI and median PC20 Underweight - 2.16 Normal Weight - 5.00 Overweight - 5.74 Obese - 2.27 No Statistical significance p=.1348

CONCLUSIONS: Some studies have shown a significant association between BMI and AHR, while others have failed to confirm this relationship in the past. Differences between sexes with regard to the influence of BMI on AHR, with a more pronounced association in females have also been documented in earlier studies. Our study here does not show any such significant association between the measure of AHR (PC20) and BMI in both sexes.

CLINICAL IMPLICATIONS: The magnitude of AHR did not appear to vary with the magnitude of BMI, suggesting no direct independent relation between them to explain the obesity - asthma association. While obesity mediated lung function changes, GERD, inflammatory mediators and hormones may explain this.

DISCLOSURE: The following authors have nothing to disclose: Karthik Vijayan, Promish Shrestha, Manuel Bautista, Lawrence Goldstein, Bhiputhi Neupane

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