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Thorax 67:A8 doi:10.1136/thoraxjnl-2012-202678.016
  • Spoken sessions
  • Targets for asthma therapy

S10 Are We Overlooking Persistent Small Airways Dysfunction in Community-Managed Asthma?

  1. BJ Lipworth1
  1. 1University of Dundee, Dundee, United Kingdom
  2. 2University of Abertay, Dundee, United Kingdom

Abstract

Background It is unknown if small airways dysfunction persists in asthmatics receiving standard community treatment. Impulse oscillometry (IOS) is a sensitive measure of small airways function. We wished to assess the degree of small airways dysfunction in a cross-section of community-managed asthmatics.

Methods We analysed primary care referral data from persistent asthmatics (n=378) receiving standard community therapy, screened using spirometry and IOS. We compared patients by British Thoracic Society asthma treatment step (2–4).

Results Step 2 were not different from step 3 patients receiving long-acting beta-agonist (LABA). Step 4 patients differed from step 2 by: higher inhaled corticosteroid (ICS) dose (p<0.0001); lower forced expiratory volume in 1s (FEV1%, p=0.02) and forced mid-expiratory flow (FEF25–75%, p=0.001); higher frequency of resonance (Fres, p=0.02) and peripheral airway resistance (R5-R20, p=0.006); while for steps 3 vs. 4, there were differences in Fres (p<0.05) and R5-R20 (p=0.006). There were high proportions of abnormality for R5-R20 (>0.03kPa/L/s) at steps 2, 3 & 4 respectively: 64.6%, 63.5% and 69.9%. Step 2 patients receiving extra-fine particle ICS demonstrated lower total airway resistance at 5Hz (R5) versus patients receiving standard ICS (124.1% vs. 138.3%, p<0.05), with no difference in FEV1 (Table 1). At step 4, R5 remained elevated at 141.3% despite concomitant LABA, with only 2.4% using extra-fine ICS.

Conclusion There is persistent small airways dysfunction despite treatment at steps 2–4 of current asthma guidelines. Extra-fine ICS may reduce airway resistance at step 2. Prospective studies with extra-fine ICS±LABA at steps 2–4 are required to discern whether improving small airways function might result in long-term improved control.

Abstract S10 Table 1