title: The prevalence and predictors of airway hyperresponsiveness in sarcoidosis.
abstract: OBJECTIVE
  Obstructive airflow limitation is the most common physiological impairment in sarcoidosis. This study determined the prevalence of airway hyperresponsiveness (AHR) in sarcoidosis, the correlation between responses to direct (using histamine) and indirect (using hypertonic saline) bronchial challenge, and the clinical, physiological and radiological predictors of AHR.
  
  
  METHODS
  Subjects with sarcoidosis and a baseline forced expiratory volume in 1 s (FEV(1)) >35% predicted underwent hypertonic and histamine challenge, lung function testing and high resolution computed tomography (HRCT) of the chest. AHR was defined as a 15% fall in FEV(1) to hypertonic saline and a 20% fall in FEV(1) to histamine.
  
  
  RESULTS
  The 52 subjects had well-preserved lung function (FEV(1) = 2.8 ± 0.7 L, 87% predicted). AHR was detected in 5/47 (11%) to hypertonic saline and 19/43 (44%) to histamine challenge. On univariate analysis, response to histamine challenge was predicted by conglomerate fibrosis (P = 0.02) and reticular pattern (P = 0.03) on HRCT. The baseline % predicted forced expiratory volume in 1 s was significantly inversely associated with AHR on univariate (P = 0.004) and multivariate analysis (P = 0.01) when adjusted by HRCT patterns.
  
  
  CONCLUSIONS
  The higher prevalence of AHR using histamine challenge than hypertonic saline challenge and the association with baseline % predicted FEV(1) suggest that the AHR in sarcoidosis may reflect the consequences of airway remodelling following inflammation.
authors.affiliation: Green Lane Respiratory Services, University of Auckland, Auckland, New Zealand. lisay@adhb.govt.nz
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Young
authors.forename: Nichola
authors.initials: N
authors.lastname: Good
authors.forename: David
authors.initials: D
authors.lastname: Milne
authors.forename: Irene
authors.initials: I
authors.lastname: Zeng
authors.forename: John
authors.initials: J
authors.lastname: Kolbe
authors.forename: Margaret L
authors.initials: ML
authors.lastname: Wilsher
mesh_terms: D000328:Adult; D056151:Airway Remodeling / Q000502:physiology*; D001249:Asthma / Q000503:physiopathology; D016535:Bronchial Hyperreactivity / Q000453:epidemiology / Q000503:physiopathology*; D001985:Bronchial Provocation Tests / Q000379:methods; D015897:Comorbidity; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012129:Respiratory Function Tests; D017565:Sarcoidosis, Pulmonary / Q000453:epidemiology / Q000503:physiopathology*