SPUTUM EOSINOPHIL COUNT IN ATHLETES WITH ANTIASTHMATIC THERAPEUTIC USE EXEMPTION

Abstract

Dear Editor-in-Chief: The prevalence of asthma has increased steadily in recent years, and it is surprisingly high in athletes (1,2,4). Although several drugs are banned in competitive sports, antiasthmatics such as beta-agonists and corticosteroids are legally admitted when administrated by metered-dose inhaler in the treatment of asthma. However, a variety of beta-adrenergic drugs, particularly clenbuterol, when administered orally or parenterally, develops an illicit activity on the myosin fibers and on the muscles (2). Accordingly, clear rules must be stated to set or verify a diagnosis of asthma in athletes to prevent cheating and harm during competition (1,2,4). Declared medications are commonplace in sports, embracing a wide series of drugs (6). However, the extraordinary number of therapeutic use exemption for antiasthmatics in sportsmen (2,4) calls for the implementation of enhanced thresholds. The diagnosis of asthma is mainly based on history of symptoms, physical examination of signs indicating the presence of bronchial obstruction, and variability in lung function spontaneously or due to bronchodilators (1). Hull et al. (4) recently highlighted that the diagnosis of asthma in athletes is particularly important because of potential implications on performance and strict regulations concerning the use of medications. Accordingly, when an athlete participates in international sports, the Joint Task Force of the European Respiratory Society and the European Academy of Allergy and Clinical Immunology recommend that a combination of medical history and laboratory tests should be documented as basis for the diagnosis of asthma and the possibility to use medications (1). Functional tests include lung function, in particular, maximum expiratory flow volume loops, with the assessment of reversibility to an inhaled beta-2 agonist such as salbutamol and the assessment of bronchial responsiveness either by a direct or by an indirect method (1). However, the use of these tests has some caveats because neither are they usually performed under direct jurisdiction of a sport medical commission nor can they be easily repeated on all athletes competing in the athletic field. Therefore, an alternative, cost-effective screening strategy should be designed (4) to verify whether therapeutic use exemptions are clinically motivated. Sputum analysis for evaluating the percentage of eosinophilia directly measures airway inflammation and objectively monitors asthma (5). Induced sputum eosinophil count was proven sensitive (90%) and specific (92%) in patients with bronchial asthma compared to subjects with asthmalike symptoms, all asthma patients presenting with eosinophil count >1% (3). At variance with blood testing, which requires a venipuncture and a dedicated apparatus for collection and handling, sputum is easily collected by noninvasive means. Moreover, eosinophil count is affordable at reasonable costs because it is routinely performed in clinical laboratories and can also be transferred to the athletic field using a common hematological analyzer. Indeed, eosinophil count in the induced sputum is not intended to replace a diagnosis on the basis of clinical signs and functional tests, but it may be a reliable and an inexpensive screening to preliminarily identify those athletes who are unlikely to suffer from asthma.