title: Comparisons of peak diurnal expiratory flow variation, postbronchodilator FEV(1) responses, and methacholine inhalation challenges in the evaluation of suspected asthma.
abstract: OBJECTIVE
  The validity of peak expiratory flow variation (PEFvar) as defined by National Heart, Lung, and Blood Institute (NHLBI) guidelines as a diagnostic tool for suspected asthma or its comparative value to methacholine inhalation challenge (MIC) or postbronchodilator (BD) FEV(1) responses has not been formally assessed. We prospectively analyzed the correlation of 28 different PEFvar indexes (including 4 NHLBI-compatible indexes) with MIC and pre-BD and post-BD FEV(1) responses in suspected asthmatic subjects with normal findings on lung examination, chest radiography, and baseline spirometry.
  
  
  METHODS
  Participants were asked to record peak expiratory flow four times daily for 2 to 3 weeks, followed by an MIC. During a minimum 6-month follow-up period, a clinical diagnosis of asthma was made or ruled out based on testing results and response to antiasthma therapy.
  
  
  METHODS
  Medical school-affiliated subspecialty private practice of allergy, asthma, and immunology.
  
  
  METHODS
  One hundred twenty-one suspected asthmatic patients with normal findings on lung examination, chest radiography, and baseline spirometry.
  
  
  RESULTS
  Fifty-seven subjects completed both the peak flow diary and the MIC and were accepted for statistical analysis. There were no statistically significant correlations between any peak expiratory flow index and MIC. Among the three diagnostic tools evaluated, MIC had the highest sensitivity (85.71%). All the PEFvar indexes and post-BD responses had low sensitivity and high false-negative rates.
  
  
  CONCLUSIONS
  PEFvar and post-BD FEV(1) responses are poor substitutes for MIC in the assessment of patients with suspected asthma with normal findings on lung examination, chest radiography, and spirometry. Our findings warrant a reconsideration of the NHLBI guidelines recommendation of the utility of PEFvar as a diagnostic tool for asthma in clinical practice.
authors: Department of Medicine and Pediatrics, Allergy and Immunology Division, MCP Hahnemann University, Philadelphia, PA, USA. gpike35@aol.com
authors: M F
authors: MF
authors: Goldstein
authors: B A
authors: BA
authors: Veza
authors: E H
authors: EH
authors: Dunsky
authors: D J
authors: DJ
authors: Dvorin
authors: G A
authors: GA
authors: Belecanech
authors: I C
authors: IC
authors: Haralabatos
mesh_terms: D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000175:diagnosis* / Q000000981:diagnostic imaging; D001985:Bronchial Provocation Tests; D016085:Bronchoconstrictor Agents / Q000493:pharmacokinetics; D001993:Bronchodilator Agents; D002648:Child; D002940:Circadian Rhythm; D005541:Forced Expiratory Volume; D006801:Humans; D016210:Methacholine Chloride; D010366:Peak Expiratory Flow Rate; D011237:Predictive Value of Tests; D011446:Prospective Studies; D013902:Radiography, Thoracic; D012129:Respiratory Function Tests; D012680:Sensitivity and Specificity; D013147:Spirometry
chemical_list: D016085:Bronchoconstrictor Agents; D001993:Bronchodilator Agents; D016210:Methacholine Chloride