The method of measuring sputum eosinophils and airway hyperresponsiveness to aid clinicians to titrate anti-inflammatory therapy for asthma has previously been described. However, measuring these biomarkers can be cumbersome and time consuming.

Smith et al evaluated whether exhaled nitric oxide (NO)—which can be quickly and easily measured with no discomfort to the patient—can help to identify optimum inhaled corticosteroid doses. Ninety seven asthmatics were randomised into a 1 year single blind, placebo controlled trial. Individuals had their inhaled corticosteroid dose altered at regular intervals, either on the basis of conventional parameters alone or with knowledge of their exhaled NO concentration. At the end of the study the mean daily dose of fluticasone was 370 µg in the NO group compared with 641 µg in the control group (p = 0.003 for the difference). No significant differences were observed in exacerbations, lung function, or sputum eosinophils.

The authors conclude that, with the help of exhaled NO measurements, inhaled corticosteroid doses can be successfully titrated down without loss of asthma control. This study raises the possibility that this easy-to-measure surrogate inflammatory biomarker can successfully tailor the inhaled corticosteroid dose in “real life” and, in turn, minimise potential local and systemic adverse sequelae. This may result in conventional parameters alone—which tend to be dissociated from the asthmatic inflammatory process—playing less of a central role.