Do Students Diagnosed with Asthma Really Have Asthma?


In many children with asthma and some without asthma, strenuous exercise causes acute narrowing of the airways, reduction in expiratory flow rates, and symptoms of wheezing that we call “Exercise Induced Asthma”.  Abrupt changes in airway temperature and humidity that occur as a result of exercise probably initiate the problem.  Limited access to specific exercise testing facilities in a doctor’s office means that in general clinical practice, diagnoses are based on reports by the child or parent that exercise produces respiratory symptoms.  However, several authors have shown poor correlation between exercise-induced asthma based on self-reported symptoms and the results of specific exercise testing.   The purpose of this study was to study the accuracy of clinically diagnosed EIA among schoolchildren.

Fifty two children in Vancouver (ages 8-14 years) referred for investigation of poorly controlled exercise-induced asthma were studied.  Following a careful history and physical examination, children performed pulmonary function tests.  These tests were given before a treadmill exercise test and repeated 5 and 15 minutes afterwards.

Only eight children (15.4%) met the full diagnostic criteria for exercise-induced asthma.  Of the remainder: 23.1% were unfit, 26.9% had vocal cord dysfunction or sighing dyspnea (a benign condition), 13.5% had a habit cough, and 21.1% had no abnormalities on clinical or laboratory testing, so were given no diagnosis.  Initial reported symptoms of wheeze or cough often changed significantly following a careful history, particularly among eight elite athletes in the study group. The final complaint was sometimes not respiratory and, in a few cases, was not even associated with exercise.

Exercise related complaints are unreliable, with patients not recognizing that they exaggerate symptoms and use jargon because it is familiar. 
(Seear M.  Archives of Disease in Childhood 2005; 90:898-902.)  -- H.T.