Physicians can better determine the most effective inhaled corticosteroid dose for children with moderate to severe allergic asthma by measuring the nitric oxide levels in the patient's breath, rather than by observing symptoms, according to a study published in the first issue for October 2005 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.

In the study, doctors based their inhaled corticosteroid treatment on exhaled nitric oxide levels, while considering symptoms, in 39 asthmatic children who were, on average, age 12. In 46 children of approximately the same age, inhaled corticosteroid levels were based on symptoms alone. All the children had atopic asthma, an allergic illness to which they have an inherited tendency.

According to the researchers, at the end of the study year, the exhaled nitric oxide-based group did not increase their steroid dose, yet they did reduce their inflammation level, as compared with the symptom group.

When explaining the new approach, the investigators noted that airways produce nitric oxide and that its fractional concentration in exhaled air is elevated in patients with atopic asthma that has not been treated with steroids. They called the nitric oxide test an "inflammometer" for the disease.

In asthma, airways narrow because of hyperreactivity to certain stimuli that produce inflammation. This narrowing can be triggered by many stimuli, including pollens, mold, animal dander, and dust mites.

During the study, exhaled nitric oxide levels were measured in one test group at each of five visits to a center over one year, while airway hyperresponsiveness and lung function were determined in both groups at the start and end of the one-year study.

Over the course of the study, the nitric oxide group had 8 severe exacerbations, as compared with 18 in the symptom group.

The researchers said that most often physicians look at symptoms to guide inhaled corticosteroid dosing in asthma. However, symptoms are nonspecific and not closely related to the presence and severity of airway inflammation. They note that symptom-based treatment could lead to excessive inhaled corticosteroid doses, while fear of side effects could lead to underdosing, especially in children.

The study appears in the first issue for October 2005 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.

The research appears in the first issue for October 2005 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.

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