Background: The aim of this study was to identify patients who benefit most from exhaled nitric oxide fraction (F ENO)-driven asthma management in primary care, based on prespecified subgroups with different levels of F ENO.
Methods: We used data from 179 adults with asthma from a 12-month primary care randomised controlled trial with 3-monthly assessments of F ENO, asthma control, medication usage, costs of medication, severe asthma exacerbations and quality of life. In the original study, patients were randomised to either a symptom-driven treatment strategy (controlled asthma (Ca) strategy) or a F ENO+symptom-driven strategy (FCa). In both groups, patients were categorised by their baseline level of F ENO as low (<25 ppb), intermediate (25-50 ppb) and high (>50 ppb). At 12 months, we compared, for each prespecified F ENO subgroup, asthma control, asthma-related quality of life, medication usage, and costs of medication between the Ca and FCa strategy.
Results: We found a difference between the Ca and FCa strategy for the mean dosage of beclomethasone strategy of 223 µg (95% CI 6-439), p=0.04) and for the total costs of asthma medication a mean reduction of US$159 (95% CI US$33-285), p=0.03) in patients with a low baseline F ENO level. No differences were found for asthma control, severe asthma exacerbations and asthma-related quality of life in patients with a low baseline F ENO level. Furthermore, in patients with intermediate or high level of F ENO, no differences were found.
Conclusions: In primary care, F ENO-driven asthma management is effective in patients with a low F ENO level, for whom it is possible to down-titrate medication, while preserving asthma control and quality of life.
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