Introduction Non-adherence, both intentional and non-intentional, is prevalent in ‘difficult to manage’ asthma and identification of patients who should respond to inhaled corticosteroids (ICS) is essential to reduce exacerbation risk and improve asthma control, but also to prevent inappropriate escalation of treatment (oral corticosteroids or biological therapies). Composite biomarker assessments (FeNO and blood eosinophils) have been shown to predict exacerbation risk in patients with asthma and these biomarkers also predict response to steroid treatment. It has previously been demonstrated that suppression of FeNO with directly observed ICS over 7 days can identify non-adherence to ICS treatment. The aim of this work was to further validate this test across UK severe asthma centres in the RASP-UK Consortium and to examine if the test can identify patients who should achieve good asthma control with better adherence to ICS treatment.
Methods Using remote monitoring technology (Vitalograph INCA™ device and Aerocrine NIOX Vero), we developed a web-based interface to deliver FeNO suppression testing in RASP-UK Severe Asthma Centres. We examined the utility of FeNO suppression testing to predict inhaled steroid responsiveness and composite biomarker profile after 30 days of monitored optimised treatment on standard high dose ICS/LABA.
Results Forty of seventy patients had a positive suppression test. Using information from the Vitalograph INCA™ server to highlight technique and timing errors, these issues were addressed and patients proceeded to 30-day monitoring of high dose ICS/LABA. A positive FeNO suppression test (Figure A) identified a biomarker-low population when adherent with high dose ICS (≥80% of inhaled steroid) whereas a negative test (Figure B) identified a biomarker-high population when adherent with high dose ICS.
Conclusion FeNO suppression testing is an effective means of identifying non-adherence to inhaled steroids in patients with difficult to manage asthma. This test can identify patients who should be optimised on inhaled steroids prior to consideration of treatment escalation.
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