Exploring the long-term utility of remotely monitored FeNO suppression testing in severe asthma.
Busby J., Holmes J., Almutairi M., Berrar-Torre I., Butler C., Chen C., Ancona GD., Dennison P., Gilbey S., Jackson DJ., Kerley S., Makhecha S., Mansur A., Nichols A-L., Patel PH., Pfeffer PE., Rupani H., Sweeney J., Heaney LG.
BACKGROUND: Confirmation of optimal inhaled corticosteroid use is essential before initiating biologic therapy. FeNO suppression testing (FeNOSuppT) is a proven phenotyping technique, however its long-term effect on clinical outcomes remains unclear. OBJECTIVES: To assess the real-world feasibility of delivering FeNOSuppT alongside digital inhaler monitoring, and to examine its effect on biologic initiation and clinical outcomes. METHODS: Prospective cohort study within seven UK severe asthma centres. Patients received a sensor-enabled ICS/LABA inhaler during an initial appointment between July 2020 and June 2022. A positive FeNOSuppT was defined as >42% FeNO reduction at short-term follow-up (typically 1-3 months post-baseline). Biologic initiation and clinical outcomes were compared at short-term and long-term (typically 12 months post-baseline) follow-up. RESULTS: Of 353 included patients, 257 (72.8%) completed the FeNOSuppT and 140 (54.5%) were positive. A positive FeNOSuppT was associated with greater improvements in short-term FEV1% (8.6% vs. -0.3, p<0.001) and ACQ6 (0.7 vs. 0.3, p=0.001) compared to a negative test. Of 168 patients eligible for biologics who completed the FeNOSuppT, those with a positive result initiated biologics less often (48.2% vs. 65.2%, p=0.035). Despite this, there was a greater improvement in FEV1 (11.0% vs. 2.3%, p=0.016), and a similar reduction in both asthma symptoms (ACQ6: 0.7 vs. 0.8, p=0.623) and exacerbations (66.7% vs. 66.7%, p=0.349) at long-term follow-up when compared to those with a negative FeNOSuppT. CONCLUSIONS: Delivering FeNOSuppT aligned with digital monitoring is feasible within routine care. A positive FeNOSuppT was associated with lower rates of biologic initiation, with similar clinical outcomes.