Diagnosis of asthma in adults

The clinical features associated with asthma are listed in Box 1. If the history is strongly suggestive of asthma, then a trial of treatment is warranted. If the trial is successful, asthma treatment should be continued.15 Objective testing to confirm the diagnosis should be considered at a later date. If the treatment is unsuccessful, or if the history is less clearly suggestive of asthma, objective testing should be performed to confirm the diagnosis. If the spirometry results are normal in such patients, further objective confirmation of asthma by measurement of airway responsiveness will validate the presence of current asthma, although it does not exclude past or future asthma. Alternative causes of symptoms suggestive of asthma (Box 2) should also be considered in the differential diagnosis of asthma. The diagnosis of asthma requires a history or current presence of respiratory signs and symptoms consistent with asthma (Box 1), combined with the objective demonstration of variable airflow obstruction. Variable airflow obstruction means that the obstruction is not necessarily present at all times, varying with time, exposure to asthma triggers and treatment. A good response to asthma treatment in a patient with a typical history of asthma supports a diagnosis of asthma.1 However, objective confirmation of the variable airflow obstruction characteristic of asthma, using spirometry or peak expiratory flow monitoring, is required, especially for patients whose response to treatment is suboptimal or whose symptoms are not highly suggestive of asthma.9,19,25-29 The key messages for the diagnosis of asthma in adults are presented in Box 4. Available tests can help the clinician to make a firm diagnosis of asthma in most patients. This common condition may well require lifelong therapy, and accurate diagnosis is therefore important. For people with a high likelihood of asthma and an appropriate response to therapy, a categorical diagnosis of asthma can be made. For such patients, confirmation with spirometry should be considered at a later date. For all others, spirometry should be part of the initial diagnostic work-up. Provocation testing may be necessary if the spirometry results are normal. The diagnosis of asthma depends on the physician's expert correlation of the patient's history, the results of a physical examination, the patient's clinical response and the results of pulmonary function testing.