Diagnosis of asthma in children under five.

Cough and wheeze are common symptoms in childhood, but mostly do not signify a serious illness. On the basis of history and examination, such children should be allocated into one of five diagnostic categories. Very few need additional tests, although there are specific pointers in the initial evaluation which should actively be sought, and result in referral for investigation. In a community setting, isolated cough with no wheeze or breathlessness is most unlikely to be due to asthma. In pre-school children who cannot perform lung function tests, a therapeutic trial of asthma treatment may be indicated, but a three step protocol is mandatory, stopping therapy if there appears to be a response, and only restarting if symptoms recur. In older children, documentation of variable airflow obstruction before giving a diagnosis of asthma is important, to avoid overdiagnosis. Prophylactic therapy on a long term basis with inhaled steroids in pre-school children does not reduce the likelihood of progression to asthma in mid-childhood, and the results of treatment in terms of symptoms are disappointing.