title: Airway responsiveness in mild to moderate childhood asthma: sex influences on the natural history.
abstract: BACKGROUND
  Airway responsiveness is a prognostic marker for asthma symptoms in later life.
  
  
  OBJECTIVE
  To evaluate characteristics responsible for persistence of airway responsiveness in children with asthma.
  
  
  METHODS
  A total of 1,041 children, initially aged 5-12 years, with mild to moderate persistent asthma enrolled in the Childhood Asthma Management Program (CAMP) were studied prospectively for 8.6 +/- 1.8 years with methacholine challenges yearly.
  
  
  RESULTS
  Least squares geometric mean models were fit to determine effects of sex and age on airway responsiveness (provocative concentration producing 20% decrease in FEV(1) [PC(20)]). Multiple linear regression analysis was performed to determine factors at baseline and over time, which were associated with PC(20) at end of follow-up. A total of 7,748 methacholine challenges were analyzed. PC(20) increased with age, with boys having greater increase after age 11 years than girls (P < 0.001). The divergence coincided with the mean age for Tanner stage 2. Postpubertal girls had greater airway responsiveness, even after adjustment for FEV(1) and other potential confounders. Although multivariable regression analyses noted a variety of factors that influenced airway responsivness in both sexes, a history of hay fever (beta= -0.30, P = 0.005), respiratory allergy (beta= -0.32, P = 0.006), or recent inhaled corticosteroid usage (beta= -0.18, P = 0.02) were associated with decrements in final log PC(20) only in girls.
  
  
  CONCLUSIONS
  Airway responsiveness (PC(20)) is more severe in the postpubertal female with asthma than in males. Although there are factors associated with airway responsiveness in both males and females, sex-specific factors may contribute to new insights into asthma pathogenesis.
authors.affiliation: Channing Laboratory, Brigham and Women's Hospital and Harvard Medical School, 181 Longwood Avenue, Boston, MA 02115, USA. kelan.tantisira@channing.harvard.edu
authors.forename: Kelan G
authors.initials: KG
authors.lastname: Tantisira
authors.forename: Ryan
authors.initials: R
authors.lastname: Colvin
authors.forename: James
authors.initials: J
authors.lastname: Tonascia
authors.forename: Robert C
authors.initials: RC
authors.lastname: Strunk
authors.forename: Scott T
authors.initials: ST
authors.lastname: Weiss
authors.forename: Anne L
authors.initials: AL
authors.lastname: Fuhlbrigge
mesh_terms: D000293:Adolescent; D000367:Age Factors; D018927:Anti-Asthmatic Agents / Q000008:administration & dosage; D001249:Asthma / Q000453:epidemiology* / Q000503:physiopathology; D016535:Bronchial Hyperreactivity / Q000453:epidemiology* / Q000503:physiopathology; D001985:Bronchial Provocation Tests; D016084:Bronchoconstriction / Q000502:physiology; D001993:Bronchodilator Agents / Q000008:administration & dosage; D019819:Budesonide / Q000008:administration & dosage; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D018450:Disease Progression; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume / Q000187:drug effects / Q000502:physiology; D006801:Humans; D016018:Least-Squares Analysis; D008297:Male; D016210:Methacholine Chloride; D017835:Nedocromil / Q000008:administration & dosage; D011379:Prognosis; D011446:Prospective Studies; D011627:Puberty / Q000502:physiology; D012744:Sex Ratio; D014797:Vital Capacity / Q000187:drug effects / Q000502:physiology
chemical_list: D018927:Anti-Asthmatic Agents; D001993:Bronchodilator Agents; D017835:Nedocromil; D016210:Methacholine Chloride; D019819:Budesonide