title: Effects of weight loss on airway responsiveness in obese adults with asthma: does weight loss lead to reversibility of asthma?
abstract: BACKGROUND
  The growing epidemics of obesity and asthma are major public health concerns. Although asthma-obesity links are widely studied, the effects of weight loss on asthma severity measured by airway hyperresponsiveness (AHR) have received limited attention. The main study objective was to examine whether weight reduction reduces asthma severity in obese adults with asthma.
  
  
  METHODS
  In a prospective, controlled, parallel-group study, we followed 22 obese participants with asthma aged 18 to 75 years with a BMI ≥ 32.5 kg/m2 and AHR (provocative concentration of methacholine causing a 20% fall in FEV1 [PC20] < 16 mg/mL). Sixteen participants followed a behavioral weight reduction program for 3 months, and six served as control subjects. The primary outcome was change in AHR over 3 months. Changes in lung function, asthma control, and quality of life were secondary outcomes.
  
  
  RESULTS
  At study entry, participant mean ± SD age was 44 ± 9 years, 95% were women, and mean BMI was 45.7 ± 9.2 kg/m2. After 3 months, mean weight loss was 16.5 ± 9.9 kg in the intervention group, and the control group had a mean weight gain of 0.6 ± 2.6 kg. There were significant improvements in PC20 (P = .009), FEV1 (P = .009), FVC (P = .010), asthma control (P < .001), and asthma quality of life (P = .003) in the intervention group, but these parameters remained unchanged in the control group. Physical activity levels also increased significantly in the intervention group but not in the control group.
  
  
  CONCLUSIONS
  Weight loss in obese adults with asthma can improve asthma severity, AHR, asthma control, lung function, and quality of life. These findings support the need to actively pursue healthy weight-loss measures in this population.
authors.affiliation: Department of Medicine, The Ottawa Hospital; University of Ottawa; Ottawa Hospital Research Institute, Ottawa, ON, Canada. Electronic address: spakhale@ohri.ca.
authors.forename: Smita
authors.initials: S
authors.lastname: Pakhale
authors.affiliation: University of Ottawa; Ottawa Hospital Research Institute, Ottawa, ON, Canada.
authors.forename: Justine
authors.initials: J
authors.lastname: Baron
authors.affiliation: Department of Medicine, The Ottawa Hospital; University of Ottawa; Ottawa Hospital Research Institute, Ottawa, ON, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: Dent
authors.affiliation: Ottawa Hospital Research Institute, Ottawa, ON, Canada.
authors.forename: Katherine
authors.initials: K
authors.lastname: Vandemheen
authors.affiliation: Department of Medicine, The Ottawa Hospital; University of Ottawa; Ottawa Hospital Research Institute, Ottawa, ON, Canada.
authors.forename: Shawn D
authors.initials: SD
authors.lastname: Aaron
mesh_terms: D000328:Adult; D001249:Asthma / Q000453:epidemiology* / Q000503:physiopathology*; D015992:Body Mass Index; D001985:Bronchial Provocation Tests; D015897:Comorbidity; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008297:Male; D016210:Methacholine Chloride / Q000009:adverse effects; D008875:Middle Aged; D009765:Obesity / Q000453:epidemiology* / Q000503:physiopathology*; D011446:Prospective Studies; D011788:Quality of Life; D012130:Respiratory Hypersensitivity / Q000139:chemically induced / Q000503:physiopathology*; D012720:Severity of Illness Index; D016896:Treatment Outcome; D014797:Vital Capacity / Q000502:physiology; D015431:Weight Loss / Q000502:physiology*
chemical_list: D016210:Methacholine Chloride