Fractional Exhaled Nitric Oxide-Assisted Management of Uncontrolled Persistent Asthma: A Real-World Prospective Observational Study.

CONTEXT: The utility of fractional exhaled nitric oxide (FeNO) measurement in real-world asthma management requires investigation.

OBJECTIVE: To determine whether FeNO-assisted care added to standard asthma management improves asthma control in a managed care organization.

DESIGN: Prospective observational study in patients aged 12 years and older with uncontrolled persistent asthma identified during a scheduled visit to an Allergy Department that routinely used FeNO (FeNO-assisted care, n = 426) vs visits to 4 Allergy Departments that did not, but followed routine guideline-based care (standard care, n = 925). The FeNO-assisted care was based on FeNO level, asthma control status, and step-care level.

MAIN OUTCOME MEASURES: Composite primary outcome was 1 or more asthma exacerbations or 7 or more dispensed canisters containing short-acting β2 -agonists in the follow-up year. Inverse probability of treatment weighting propensity scoring balanced covariates, and multivariable regression analyses compared outcomes between groups.

RESULTS: Compared with standard care, FeNO-assisted care was not associated with reducing the primary composite outcome (adjusted risk ratio = 0.94, 95% confidence interval = 0.69-1.29, p = 0.71), nor with a reduction in asthma exacerbations or dispensing of 7 or more short-acting β2 -agonist canisters as separate outcomes. In an atopic subgroup with aeroallergen sensitization, the composite outcome was similar between groups, but the rate of asthma exacerbations was lower with FeNO-assisted treatment (adjusted rate ratio = 0.67, 95% confidence interval = 0.49-0.91, p = 0.01).

CONCLUSION: These findings suggest future studies of FeNO-assisted care should be directed at the atopic phenotype.