To the Editors:
In the original article by Ponsioen et al. 1, there is no mention of the predictive value of the type of airway inflammation that is associated with cough, or whether there was any benefit from inhaled corticosteroid treatment.
There is increasing evidence that eosinophilic airway inflammation, i.e. an eosinophilic bronchitis, which can be identified from spontaneous or induced sputum cell counts, predicts the benefit from corticosteroid treatment in chronic cough, asthma and chronic obstructive pulmonary disease and that a lack of eosinophilia indicates an absence of any benefit 2–6.
An eosinophilic bronchitis occurs in only 10–30% of patients referred to a specialist with an isolated chronic cough 7–9. Hence, in an unselected population of patients with cough, the majority of whom will not have eosinophilic bronchitis, the benefit from inhaled steroid treatment is likely to be small, as indicated in the study by Ponsioen et al. 1, or absent. Measurement of airway inflammation is necessary to interpret the results of treatment with anti-inflammatory medications.
References
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Ponsioen BP, Hop WCJ, Vermue NA, Dekhuijzen PNR, Bohnen AM. Efficacy of fluiticasone on cough: a randomised controlled trial. Eur Respir J 2005;145:147–152.
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Gibson PG, Dolovich J, Denburg J, Ramsdale EH, Hargreave FE. Chronic cough: eosinophilic bronchitis without asthma. Lancet 1989;17:1346–1348.
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Pavord ID, Brightling CE, Wolkman G, Wardlaw AJ. Non-eosinophilic corticosteroid unresponsive asthma. Lancet 1999;353:2213–2214.
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Pizzichini E, Pizzichini MM, Gibson P, et al. Sputum eosinophilia predicts benefit from prednisone in smokers with chronic obstructive bronchitis. Am J Respir Crit Care Med 1998;158:1511–1517.
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Pizzichini MM, Pizzichini E, Parameswaran K, et al. Non-asthmatic chronic cough: no effect of treatment with an inhaled corticosteroid in patients without sputum eosinophilia. Can Respir J 1999;6:323–330.
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Brightling CE, Ward R, Goh KL, Wardlaw AJ, Pavord ID. Eosinophilic bronchitis is an important cause of cough. Am J Respir Crit Care Med 1999;160:406–410.
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Carney IK, Gibson PG, Murnee-Allen K, Saltos N, Olson LG, Hensley MJ. A systematic evaluation of mechanisms in chronic cough. Am J Respir Crit Care Med 1997;156:211–216.
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Ayik SO, Basoglu OK, Erdinc M, Bor S, Veral A, Bilgen A. Eosinophilic bronchitis as a cause of chronic cough. Respir Med 2003;97:695–701.
