What Is New In Small Airways Research
By Ves Dimov, MD
Allergist/Immunologist, Assistant Professor of Pediatrics, University of Chicago
Editor, WAO Small Airways Working Group website
Posted 16 November 2011
Leukotriene receptor antagonist (LTRA) montelukast is an option for step-down therapy for mild asthmatics controlled on low-dose inhaled corticosteroids (ICS). Some patients fail montelukast step-down therapy, it would be helpful to predict this risk. The Leukotriene or Corticosteroid or Corticosteroid-Salmeterol Study (LOCCS) trial included 165 participants. Characteristics independently associated with montelukast treatment failure included:
- age of asthma onset <10 years old (OR = 2.39)
- need for steroid burst in the last year (OR = 2.39)
- pre-bronchodilator forced expiratory volume in 1 s (FEV1) (OR = 1.44 per 10% lower % predicted)
The montelukast failure index was basaed on these 3 variables (range: −5 to 7 points):
- scores <0 predicted low risk (<0.20) of treatment failure
- scores >5 predicted high risk (>0.60) of treatment failure
Early asthma onset, worse asthma control in the last year, and lower FEV1 are associated with montelukast treatment failure. A montelukast failure index is proposed to quantify the risk of failure prior to treatment initiation.
Source: Drummond MB, Peters SP, Castro M, Holbrook JT, Irvin CG et al. Risk Factors for Montelukast Treatment Failure in Step-Down Therapy for Controlled Asthma. Journal of Asthma. 2011; posted online October 27 (doi:10.3109/02770903.2011.627488)
Patients with persistent airway obstruction due to refractory asthma have neutrophil-dominant airway inflammation
Neutrophilic inflammation in refractory asthma may increase the likelihood of non-responsiveness to inhaled corticosteroids (ICS), even at higher doses. This Korean study recruited 77 patients with refractory asthma from a cohort of 2,298 asthmatics.
The group with persistent airway obstruction had a longer duration of asthma and a higher frequency of near fatal asthma despite the higher doses of inhaled corticosteroids. Neutrophilic inflammation was predominant In the group with persistent airway obstruction (PAO), whereas eosinophilic inflammation was predominant in the non-PAO group (P= 0.003).
Patients with persistent airway obstruction due to refractory asthma show different clinical manifestations and have neutrophil-dominant airway inflammation. This may provide the rationale for developing new asthma medications for individualized therapy.
Source: Choi JS, Jang AS, Park JS, Park SW, Paik SH et al. Role of neutrophils in persistent airway obstruction due to refractory asthma. Respirology. 2011; Accepted, unedited 31 October (doi: 10.1111/j.1440-1843.2011.02097.x.)
Single dose of dexamethasone as effective as a 5-day course of oral steroids for asthma exacerbations in children
Traditionally, mild-to-moderate pediatric asthma exacerbations have been treated with a short course of oral steroids – often 5 days of prednisone or prednisolone. A similar outcome can be acheived with a single dose of dexamethasone, which has a longer half-life and powerful anti-inflammatory effects, along with easier administration and compliance.
Oral administration of dexamethasone is the preferred route, especially considering the 80% bioavailability. One study followed 110 children at 5 days after randomization to either a single dose of oral dexamethasone (0.6 mg/kg, maximum 18 mg) or oral prednisolone (1 mg/kg per dose, maximum 30 mg) twice daily for 5 days. Overall, hospital admission rates at 5 days did not differ significantly between dexamethasone and prednisolone. Patient self-assessment scores returned to baseline in 5 days in both groups.
Most of the single-dose dexamethasone studies also point out its compliance advantage over multiple days of prednisone.
Source: Cross KP, Paul RI, Goldman RD. Single-dose dexamethasone for mild-to-moderate asthma exacerbations: Effective, easy, and acceptable. Canadian Family Physician. 2011;57(10):1134-6.
Posted 16 November 2011