title: Obesity can influence children's and adolescents' airway hyperresponsiveness differently.
abstract: BACKGROUND
  Literature is still arguing about a possible relationship between airway hyperresponsiveness (AHR) and body mass index (BMI). This study aimed at evaluating the influence of BMI on AHR and pulmonary function in children and adolescents that performed a methacholine test for suggestive asthma symptoms.
  
  
  METHODS
  799 consecutive children/adolescents (535 M; mean age: 15 ± 3 yrs; median FEV1% predicted: 101.94% [93.46-111.95] and FEV1/FVC predicted: 91.07 [86.17-95.38]), were considered and divided into underweight, normal, overweight and obese. Different AHR levels were considered as moderate/severe (PD20 ≤ 400 μg) and borderline (PD20 > 400 μg).
  
  
  RESULTS
  536 children/adolescents resulted hyperreactive with a median PD20 of 366 μg [IQR:168-1010.5]; 317 patients were affected by moderate/severe AHR, whereas 219 showed borderline hyperresponsiveness. Obese subjects aged > 13 years showed a lower (p = 0.026) median PD20 (187μg [IQR:110-519]) compared to overweight (377 μg [IQR:204-774]) and normal-weight individuals' values (370.5 μg [IQR:189-877]). On the contrary, median PD20 observed in obese children aged ≤ 13 years (761 μg [IQR:731-1212]) was higher (p = 0.052) compared to normal-weight children's PD20 (193 μg [IQR:81-542]) and to obese adolescents' values (aged > 13 years) (p = 0.019). Obesity was a significant AHR risk factor (OR:2.853[1.037-7.855]; p = 0.042) in moderate/severe AHR adolescents. Females showed a higher AHR risk (OR:1.696[1.046-2.751] p = 0.032) compared to males. A significant relationship was found between BMI and functional parameters (FEV1, FVC, FEV1/FVC) only in hyperreactive females.
  
  
  CONCLUSIONS
  Obesity seems to influence AHR negatively in female but not in male adolescents and children. In fact, AHR is higher in obese teenagers, in particular in those with moderate/severe hyperresponsiveness, and may be mediated by obesity-associated changes in baseline lung function.
authors.affiliation: Unit of Pneumology, Azienda Ospedaliera, "Misericordia" Hospital, Via Senese 161, 58100, Grosseto, Italy. bsposat@tin.it.
authors.forename: Bruno
authors.initials: B
authors.lastname: Sposato
authors.forename: Marco
authors.initials: M
authors.lastname: Scalese
authors.forename: Maria Giovanna
authors.initials: MG
authors.lastname: Migliorini
authors.forename: Maria Piera
authors.initials: MP
authors.lastname: Riccardi
authors.forename: Massimo Tosti
authors.initials: MT
authors.lastname: Balducci
authors.forename: Luigi
authors.initials: L
authors.lastname: Petruzzelli
authors.forename: Raffaele
authors.initials: R
authors.lastname: Scala
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