Personalised exhaled nitric oxygen fraction (F(ENO))-driven asthma management in primary care: a F(ENO) subgroup analysis of the ACCURATE trial

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.