Claude S Farah1, Jessica A Kermode2, Sue R Downie2, Nathan J Brown2, Kate M Hardaker2, Norbert Berend2, Gregory G King3, Cheryl M Salome2. 1. Woolcock Institute of Medical Research, Glebe, Australia; Cooperative Research Centre for Asthma and Airways, Glebe, Australia; University of Sydney, Sydney, Australia. Electronic address: cfarah@med.usyd.edu.au. 2. Woolcock Institute of Medical Research, Glebe, Australia; Cooperative Research Centre for Asthma and Airways, Glebe, Australia; University of Sydney, Sydney, Australia. 3. Woolcock Institute of Medical Research, Glebe, Australia; Cooperative Research Centre for Asthma and Airways, Glebe, Australia; University of Sydney, Sydney, Australia; Department of Respiratory Medicine, Royal North Shore Hospital, St. Leonards, NSW, Australia.
Abstract
BACKGROUND: It is unclear why obesity is associated with worse asthma control. We hypothesized that (1) obesity affects asthma control independent of spirometry, airway inflammation, and airway hyperresponsiveness (AHR) and (2) residual symptoms after resolution of inflammation are due to obesity-related changes in lung mechanics. METHODS: Forty-nine subjects with asthma underwent the following tests, before and after 3 months of high-dose inhaled corticosteroid (ICS) treatment: five-item asthma control questionnaire (ACQ-5), spirometry, fraction of exhaled nitric oxide (Feno), methacholine challenge, and the forced oscillation technique, which allows for the calculation of respiratory system resistance (Rrs) and respiratory system reactance (Xrs) as indicators of airway caliber and elastic load, respectively. The effects of treatment were assessed by BMI group (18.5-24.9, 25-29.9, and ≥ 30 kg/m²) using analysis of variance. Multiple regression analyses determined the independent predictors of ACQ-5 results. RESULTS: At baseline, the independent predictors of ACQ-5 results were FEV(1), Feno, and BMI (model r² = 0.38, P < .001). After treatment, asthma control, spirometry, airway inflammation, and AHR improved similarly across BMI groups. The independent predictors of ACQ-5 results after treatment were Rrs and BMI (model r² = 0.42, P < .001). CONCLUSIONS: BMI is a determinant of asthma control independent of airway inflammation, lung function, and AHR. After ICS treatment, BMI again predicts ACQ-5 results, but independent of obesity-related changes in lung mechanics.
BACKGROUND: It is unclear why obesity is associated with worse asthma control. We hypothesized that (1) obesity affects asthma control independent of spirometry, airway inflammation, and airway hyperresponsiveness (AHR) and (2) residual symptoms after resolution of inflammation are due to obesity-related changes in lung mechanics. METHODS: Forty-nine subjects with asthma underwent the following tests, before and after 3 months of high-dose inhaled corticosteroid (ICS) treatment: five-item asthma control questionnaire (ACQ-5), spirometry, fraction of exhaled nitric oxide (Feno), methacholine challenge, and the forced oscillation technique, which allows for the calculation of respiratory system resistance (Rrs) and respiratory system reactance (Xrs) as indicators of airway caliber and elastic load, respectively. The effects of treatment were assessed by BMI group (18.5-24.9, 25-29.9, and ≥ 30 kg/m²) using analysis of variance. Multiple regression analyses determined the independent predictors of ACQ-5 results. RESULTS: At baseline, the independent predictors of ACQ-5 results were FEV(1), Feno, and BMI (model r² = 0.38, P < .001). After treatment, asthma control, spirometry, airway inflammation, and AHR improved similarly across BMI groups. The independent predictors of ACQ-5 results after treatment were Rrs and BMI (model r² = 0.42, P < .001). CONCLUSIONS: BMI is a determinant of asthma control independent of airway inflammation, lung function, and AHR. After ICS treatment, BMI again predicts ACQ-5 results, but independent of obesity-related changes in lung mechanics.
Authors: Luisa N Borrell; Elizabeth A Nguyen; Lindsey A Roth; Sam S Oh; Haig Tcheurekdjian; Saunak Sen; Adam Davis; Harold J Farber; Pedro C Avila; Emerita Brigino-Buenaventura; Michael A Lenoir; Fred Lurmann; Kelley Meade; Denise Serebrisky; William Rodriguez-Cintron; Rajesh Kumar; Jose R Rodriguez-Santana; Shannon M Thyne; Esteban G Burchard Journal: Am J Respir Crit Care Med Date: 2013-04-01 Impact factor: 21.405