title: Correlation of airway hyper-responsiveness with obstructive spirometric indices and FEV(1) > 90% of predicted.
abstract: BACKGROUND
  Current published guidelines on spirometry interpretation suggest an elevated FVC and FEV(1) > 100% of predicted with an obstructive ratio may represent a physiological variant. There is minimal evidence whether this finding can be indicative of symptomatic airways  obstruction.
  
  
  METHODS
  Pulmonary function testing databases for a 4-year period were retrospectively reviewed. All technically adequate spirometry studies were included, based on these criteria: FEV(1) > 90% of predicted, and FEV(1)/FVC below the lower limit of normal,  based on 95th percentile confidence intervals. Clinical indications for testing were noted. Testing for post-bronchodilator response, lung volumes, and methacholine challenge tests were reviewed for evidence of airway hyper-responsiveness (AHR). Comparisons were made between symptomatic versus  asymptomatic individuals and FEV(1) values less than or greater than 100% of predicted.
  
  
  RESULTS
  A total of 280 studies were analyzed. During their clinical evaluation, 192 patients (69%) had post-bronchodilator spirometry recorded, 63 patients (23%) had lung volumes, and 36 patients  (11%) completed methacholine challenge testing. Indications for spirometry included 193 symptomatic patients and 87 asymptomatic patients. Nearly 28% of patients with post-bronchodilator testing met criteria for AHR. No differences in AHR were found between the symptomatic and asymptomatic  groups. The majority of patients (77%) with AHR had an FEV(1) < 100%, when compared to patients with an FEV(1) ≥ 100%.
  
  
  CONCLUSIONS
  A normal FEV(1) > 90% of predicted with obstructive indices may not represent a normal physiological variant, as 28% of patients  were found to have underlying AHR. These findings suggest that clinicians should evaluate for AHR, especially in symptomatic patients, even if the FEV(1) is > 90% of predicted.
authors: Keesler Medical Center, Keesler Air Force Base, Biloxi, MS, USA.
authors: George H
authors: GH
authors: Kotti
authors: David G
authors: DG
authors: Bell
authors: Tokunbo
authors: T
authors: Matthews
authors: Pedro F
authors: PF
authors: Lucero
authors: Michael J
authors: MJ
authors: Morris
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000402:Airway Obstruction / Q000175:diagnosis / Q000503:physiopathology*; D016535:Bronchial Hyperreactivity / Q000175:diagnosis* / Q000503:physiopathology*; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D012129:Respiratory Function Tests / Q000592:standards; D012189:Retrospective Studies; D013147:Spirometry; D055815:Young Adult