Asthma exacerbations and sputum eosinophil counts

Abstract

Ruth Green and colleagues (Nov 30, p 1715)1Green RH Brightling CE McKenna S et al.Asthma exacerbations and sputum eosinophil counts: a randomised controlled trial.Lancet. 2002; 360: 1715-1721Summary Full Text Full Text PDF PubMed Scopus (1450) Google Scholar show that use of a management strategy targeted against sputum eosinophilia leads to significantly fewer severe exacerbations of asthma than standard guidelines alone. Moreover, they find that the effects on eosinophils and other inflammatory markers are disconnected from lung function and symptoms. We would like to raise two points. The use of combined inhaled corticosteroid and long-acting β2 agonist inhalers, favoured by current guidelines at step 3, will always have a greater effect on bronchodilator-sensitive variables such as peak expiratory flow and rescue use, than on inflammatory markers and airway hyper-responsiveness.2Aziz I Wilson AM Lipworth BJ Effects of once-daily formoterol and budesonide given alone or in combination on surrogate inflammatory markers in asthmatic adults.Chest. 2000; 118: 1049-1058Crossref PubMed Scopus (65) Google Scholar In other words, use of a lower dose of inhaled corticosteroid while adding a longacting β2 agonist will give the impression of adequate control in terms of smooth muscle outcomes such as measures of airway calibre, without providing any real information on the underlying inflammatory process. We also wonder about the practicality of sputum induction in everyday clinical practice, especially in terms of obtaining instant feedback of the result for the patient in the clinic. Since effects on airway eosinophils and methacholine hyper-responsiveness are closely related,1Green RH Brightling CE McKenna S et al.Asthma exacerbations and sputum eosinophil counts: a randomised controlled trial.Lancet. 2002; 360: 1715-1721Summary Full Text Full Text PDF PubMed Scopus (1450) Google Scholar, 3Sont JK Han J van Krieken JM et al.Relationship between the inflammatory infiltrate in bronchial biopsy specimens and clinical severity of asthma in patients treated with inhaled steroids.Thorax. 1996; 51: 496-502Crossref PubMed Scopus (208) Google Scholar methacholine challenge might be more practical (an abbreviated challenge takes less than 30 min4Cockcroft DW Marciniuk DD Hurst TS et al.Methacholine challenge: test-shortening procedures.Chest. 2001; 120: 1857-1860Crossref PubMed Scopus (46) Google Scholar), is simple, and is relatively inexpensive. This test could be done to optimise anti-inflammatory therapy in patients with more severe uncontrolled asthma for whom either increasing the dose of inhaled corticosteroid or adding in non-steroidal anti-inflammatory treatment might be beneficial.5Currie GP, Lee DK, Haggart K, Bates CE, Lipworth BJ. Effects of montelukast on surrogate inflammatory markers in corticosteroid treated asthmatics. Am J Respir Crit Care Med (in press). http://ajrccm.atsjournals.org/articlesinpress.shtml DOI: 10.1164/rccm.200209-11160C (accessed March, 2003).Google Scholar Asthma exacerbations and sputum eosinophil countsAuthors' reply Full-Text PDF