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What Is New In Small Airways Research

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By Ves Dimov, MD
Assistant Professor of Medicine and Pediatrics
University of Chicago

Corticosteroid/beta-agonist combo inhaler as reliever therapy: A solution for mild asthma?

The recommended treatment of mild asthma is regular maintenance inhaled corticosteroids (ICSs) and a short-acting β-agonist as a separate inhaler used when needed for symptom relief. However, the benefits of regular ICS use in actual clinical practice are limited by poor adherence and low prescription rates.

An alternative strategy would be the symptom-driven (as-required, or "prn") use of a combination ICS/short-acting β-agonist or ICS/long-acting β-agonist inhaler (formoterol) as a reliever rather than regular maintenance use. The rationale for this approach is to titrate both the ICS and β-agonist dose according to need. This may enhance ICS use in otherwise poorly adherent patients who over rely on their reliever β-agonist inhaler alone.

There is evidence to suggest that this regimen has advantages over regular ICS therapy for the treatment of mild asthma.

Source: Beasley R, Weatherall M, Shirtcliffe P, Hancox R, Reddel HK. Combination corticosteroid/β-agonist inhaler as reliever therapy: A solution for intermittent and mild asthma? Journal of Allergy and Clinical Immunology 2014; 133(1):39-41. doi: 10.1016/j.jaci.2013.10.053.

Image source: Airway during asthma symptoms, National Institutes of Health (NIH) and Wikipedia; public domain.

Perinatal risk factors for persistent wheezing in the first 8 years of life: male gender, parental allergy, not receiving breastfeeding

This study from The Netherlands used a data-driven approach to identify 5 wheezing phenotypes among almost 4,000 preschool children aged 0-8 years, in the Prevention and Incidence of Asthma and Mite Allergy (PIAMA) birth cohort: never/infrequent wheeze, transient early wheeze, intermediate onset wheeze, persistent wheeze and late onset wheeze.

Perinatal factors were collected at 3 months, and wheezing was assessed annually until the age of 8 years. Complete data were available for 2,728 children.

Risk factors for transient early wheeze (n = 455) were male gender, maternal and paternal allergy, low maternal age, high maternal body mass index, short pregnancy duration, smoking during pregnancy, presence of older siblings and day-care attendance. Risk factors for persistent wheeze (n = 83) were male gender, maternal and paternal allergy, and not receiving breastfeeding for at least 12 weeks.

This study identified risk factors for specific childhood wheezing phenotypes. It is very important that some them are potentially modifiable, for example, maternal age and body mass index, smoking, day-care attendance, and breastfeeding. The modifiable risk factors can be targeted by prevention programs.

Source: Caudri D, Savenije OEM, Smit HA, Postma DS, Koppelman GH, Wijga AH, Kerkhof M et al. Perinatal risk factors for wheezing phenotypes in the first 8 years of life. Clinical and Experimental Allergy 2013; 43(12):1395-405. doi: 10.1111/cea.12173.

Small airway targeted therapy in pediatric asthma: Are we there yet?

The short answer is: no. Targeting small airways (less than 2 mm in diameter) in the management of asthma has received more attention recently. Clinicians need to be aware of small airway inflammation especially in patients with severe or nocturnal asthma.

Increased resistance of small airways may be assessed noninvasively by spirometry, nitrogen wash out, body plethysmography, impulse oscillometry (IOS), and using imaging (high resolution computed tomography or conventional chest X-ray).

The use of metered-dose inhaler (MDI) products with extrafine particles of inhaled corticosteroids has been suggested for targeted therapy of small airways. However, studies in pediatrics have generally been inconclusive.

Source: Raissy HH, Blake K. Small airway targeted therapy in pediatric asthma: Are we there yet? Pediatric Allergy Immunology and Pulmonology 2013; 26(4): 204-206.

Last updated: Thursday, May 14th, 2015