F _eNO-based asthma management results in faster improvement of airway hyperresponsiveness

Asthma is characterised by inflammation and respiratory symptoms. Current asthma treatment is based on severity of asthma symptoms only. Exhaled nitric oxide fraction (F _eNO) is not recommended by the Global Initiative for Asthma guidelines. The aim was to compare the usefulness of a F _eNO guided versus symptom-based treatment in achieving improved asthma control assessed by airway hyperresponsiveness (AHR). 80 asthmatic patients were included in a double-blinded, parallel, randomised controlled trial with follow-up visits after 8, 24 and 36 weeks. Treatment was tailored using either a F _eNO or Asthma Control Questionnaire (ACQ) based algorithm. Inclusion criteria were asthma symptoms and a provocative dose causing a 15% fall in forced expiratory volume in 1 s <635 mg mannitol. At each visit AHR, F _eNO, ACQ and blood tests were performed. No differences between the two groups were found at inclusion. AHR from 8 to 24 weeks was improved in the F _eNO group compared to the ACQ group (response dose ratio (RDR) geometric mean (95% CI): 0.02 (0.01-0.04) versus 0.05 (0.03-0.07), respectively, p=0.015). AHR to mannitol at 36 weeks showed no differences between the two groups (mean difference RDR (95% CI): -0.02 (-0.05-0.02), p=0.3). Total doses of inhaled steroid and number of exacerbations were similar (p>0.05). When using F _eNO as a treatment management tool, lowering of airway responsiveness occurred earlier than using ACQ. However, airway responsiveness and asthma control after 9 months were similar.