Copyright ©ERS Journals Ltd 2005 Airway responsiveness to hypertonic saline: dose-response slope or PD15?1 Institute for Risk Assessment Sciences, Environmental and Occupational Health, Utrecht University, Utrecht, and 2 Childhood Pulmonology, Erasmus Medical Centre, Rotterdam, The Netherlands. 3 Woolcock Institute of Medical Research, Sydney, New South Wales, Australia CORRESPONDENCE: G. de Meer, Institute for Risk Assessment Sciences, Environmental and Occupational Health, Utrecht University, P.O. Box 80176, 3508 TD Utrecht, The Netherlands. Fax: 31 302535077. E-mail: G.demeer@iras.uu.nl Keywords: Airway hyperresponsiveness, childhood asthma, dose-response slope, epidemiology, hypertonic saline, provocative dose causing a 15% fall in forced expiratory volume in one second
Received: January 21, 2004
The result of airway challenge test with hypertonic saline (HS) is expressed as the dose causing a 15% fall in forced expiratory volume in one second (FEV1; PD15). A noncensored measure, such as the dose-response slope (DRS), allows the evaluation of the risk of asthma for subjects with a fall in FEV1 <15%. The aim of this study was to assess the relationship between airway responsiveness to HS by PD15 or DRS, asthma symptoms and markers of eosinophilic inflammation.
Data on current wheeze and airway responsiveness were obtained for 1,107 children (aged 813 yrs). Blood eosinophils and serum eosinophil cationic protein (ECP) were assessed in subsets (n = 683 and 485). PD15 was assessed if FEV1 fell
Children with features of asthma had lower PD15 and higher DRS, and separation was most pronounced for DRS. Prevalence of current wheeze increased continuously over the entire range of DRS values. Blood eosinophils were significantly higher only for the highest values of DRS.
In conclusion, the continuous relationship between airway responsiveness and asthma symptoms is in favour of a noncensored measure of airway responsiveness, such as the dose-response slope.
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