title: Airways resistance and specific conductance for the diagnosis of obstructive airways diseases.
abstract: BACKGROUND
  Airway resistance (RAW) and specific airway conductance (sGAW) are measures that reflect the patency of airways. Little is known of the variability of these measures between different lung diseases. This study investigated the contribution of RAW and sGAW to a diagnosis of obstructive airways disease and their role in differentiating asthma from COPD.
  
  
  METHODS
  976 subjects admitted for the first time to a pulmonary practice in Belgium were included. Clinical diagnoses were based on complete pulmonary function tests and supported by investigations of physicians' discretion. 651 subjects had a final diagnosis of obstructive diseases, 168 had another respiratory disease and 157 subjects had no respiratory disease (healthy controls).
  
  
  RESULTS
  RAW and sGAW were significantly different (p < 0.0001) between obstructive and other groups. Abnormal RAW and sGAW were found in 39 % and 18 % of the population, respectively, in which 81 % and 90 % had diagnosed airway obstruction. Multiple regression revealed sGAW to be a significant and independent predictor of an obstructive disorder. To differentiate asthma from COPD, RAW was found to be more relevant and statistically significant. In asthma patients with normal FEV1/FVC ratio, both RAW and sGAW were more specific than sensitive diagnostic tests in differentiating asthma from healthy subjects.
  
  
  CONCLUSIONS
  RAW and sGAW are significant factors that contribute to the diagnosis and differentiation of obstructive airways diseases.
authors.affiliation: Department of Clinical and Experimental Medicine, Laboratory of Respiratory Diseases, University Hospital Leuven, KULEUVEN University of Leuven, Herestraat 49, 3000, Leuven, Belgium.
authors.forename: Marko
authors.initials: M
authors.lastname: Topalovic
authors.affiliation: Respiratory Division, University Hospital Ghent, University of Ghent, Ghent, Belgium.
authors.forename: Eric
authors.initials: E
authors.lastname: Derom
authors.affiliation: Department of Rehabilitation Sciences, Faculty of Kinesiology and Rehabilitation Sciences, KU Leuven, Leuven, Belgium.|Department of Physiotherapy, Monash University, Victoria, Australia.|Institute for Breathing and Sleep, Victoria, Australia.|Monash Health, Monash Lung and Sleep, Victoria, Australia.
authors.forename: Christian R
authors.initials: CR
authors.lastname: Osadnik
authors.affiliation: Department of Clinical and Experimental Medicine, Laboratory of Respiratory Diseases, University Hospital Leuven, KULEUVEN University of Leuven, Herestraat 49, 3000, Leuven, Belgium.|Department of Rehabilitation Sciences, Faculty of Kinesiology and Rehabilitation Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Thierry
authors.initials: T
authors.lastname: Troosters
authors.affiliation: Department of Clinical and Experimental Medicine, Laboratory of Respiratory Diseases, University Hospital Leuven, KULEUVEN University of Leuven, Herestraat 49, 3000, Leuven, Belgium.
authors.forename: Marc
authors.initials: M
authors.lastname: Decramer
authors.affiliation: Department of Clinical and Experimental Medicine, Laboratory of Respiratory Diseases, University Hospital Leuven, KULEUVEN University of Leuven, Herestraat 49, 3000, Leuven, Belgium. Wim.Janssens@uzleuven.be.
authors.forename: Wim
authors.initials: W
authors.lastname: Janssens
mesh_terms: D000328:Adult; D000368:Aged; D000402:Airway Obstruction / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology*; D000403:Airway Resistance / Q000502:physiology*; D001530:Belgium / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012129:Respiratory Function Tests / Q000379:methods