© 2005 American Thoracic Society
Efficacy of Fluticasone Propionate on Lung Function and Symptoms in Wheezy InfantsFrom the Authors:We agree with Dr. Ponsioen and colleagues that some questions remain after our study, but the explanation that lung function in wheezy infants did not improve following fluticasone is incorrect. Sufficient room for lung function improvement was an inclusion criterion (1), and 92% of the infants had a baseline VmaxFRC z-score below zero. Nevertheless, the lung function tests we used may still not be sensitive enough to demonstrate an improvement explaining and corresponding with the observed clinical improvement. We agree that the significant improvements in cough, wheeze, and dyspnea after 6 weeks compared with placebo are suggestive of a therapeutic effect, but because this beneficial effect was not present after 13 weeks, we did not consider this as clinically relevant for a long-term treatment. However, if there is real symptomatic improvement due to fluticasone after 6 weeks, there are obvious similarities between the results of Ponsioen and coworkers (2) and ours. The causes of cough and airway obstruction may not only involve airway inflammation; increased secretion and/or decreased clearance of mucus may play a significant role as well. Passive smoking may be a relevant factor: it may make these infants more vulnerable to viral infections (3), and parents who smoke may be less aware of asthma symptoms in their children (4), thereby reporting lower symptom scores. These factors may mask any effects of inhaled corticosteroids and result in underestimation of symptoms. In our study, possibly due to small numbers, we could not demonstrate that indoor parental smoking had a modifying effect on the relationship between treatment and lung function, nor between symptoms and bronchodilator use. As expected, we observed a positive correlation between changes of bronchodilator use and of changes of cough scores, but from this one cannot infer a causal relationship. Interventional studies in infants with asthmalike symptoms remain difficult to conduct and interpret: the presenting symptoms can be atypical; the majority of wheezy children younger than 2 years of age have respiratory symptoms due to other causes; and most wheezy infants do not demonstrate an improvement of symptoms or lung function after inhaled bronchodilators (5), and have no "RAST positivity." Hence, it may be that the majority of wheezy infants will not benefit from maintenance treatment with inhaled corticosteroids. The challenge for the future remains how to recognize those wheezy infants who have, or will develop, allergic asthma and will improve on anti-inflammatory treatment.
Erasmus Medical Centre, Rotterdam, The Netherlands FOOTNOTES Conflict of Interest Statement: None of the authors have a financial relationship with a commercial entity that has an interest in the subject of this manuscript. REFERENCES
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