Small airways disease is highly prevalent in asthma (50-60%), even in patients with milder disease

This systematic literature review co-authored by PJ Barnes evaluated the prevalence of small airways disease in adult asthma. Small airways dysfunction and inflammation contribute to clinical impact of asthma, yet conventional methods of assessing airways function cannot reliably evaluate its presence.

15 publications were identified determining the prevalence of small airways disease in asthma. Methods of assessments included:

- impulse oscillometry
- spirometry
- body plethysmography
- multiple-breath nitrogen washout
- high-resolution computed tomography

The prevalence of small airways disease was 50-60% among patients with asthma. Small airways disease was present across all asthma severities, with evidence of distal airway disease even in the absence of proximal airway obstruction.

References:

The prevalence of small airways disease in adult asthma: A systematic literature review. Usmani OS et al. Respir Med. 2016 Jul;116:19-27. doi: 10.1016/j.rmed.2016.05.006. Epub 2016 May 7.
http://www.resmedjournal.com/article/S0954-6111(16)30082-8/fulltext
(free full text)

The World Allergy Organization (WAO) Small Airways Working Group publishes a monthly "What's New?" summary and I have served as its editor since 2011. The summary features the top 3 asthma/small airways articles each month. The article above is a part of the project. The archive is here: http://www.worldallergy.org/small_airways_group/reviews/archive.php

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