30-Days Spirometry Holter: a novel tool for objective asthma diagnosis

<bold>Introduction:</bold> Asthma underdiagnosis and overdiagnosis remain significant problems for healthcare systems worldwide and indicate considerable pain points with current guidelines and diagnostic methods; therefore, new, targeted approaches seem crucial. This study introduces a novel spirometry-based approach using digital tools for objective asthma diagnosis. <bold>Methods:</bold> This was a single-centre (Warsaw Medical University), observational, prospective study. Inclusion criteria included adults with suspected asthma per GINA 2020, without confirmed obstruction in ambulatory spirometry. Patients were equipped and trained with a Portable spirometer AioCare® (HealthUp, Warsaw). The protocol included twice-daily spirometry examinations over four weeks and symptom reporting in the mobile app. The number of obstructions detected, probability of finding obstruction over time, spirometry values' variability, technical correctness, and reported symptoms were evaluated. <bold>Results:</bold> 26 patients were recruited (14 females, mean age 37.6 y.o, BMI 24.7 kg/m^2), with a primary outcome of observed obstruction in 42% of participants (3,08 per patient, 95%CI: 0.78 - 5.37). The detection probability of obstruction plateaued at 100% within the first 21 days of monitoring. Diurnal PEF and FEV1 variability were exceeded (≥10%) in 73% and 66% of patients, respectively. 88% of participants performed over half of their tests correctly. 85% of patients reported symptoms at least once. <bold>Conclusions:</bold> The Spirometry Holter is a novel and feasible tool for monitoring airway limitation variability in line with GINA, showing promise in the objective confirmation of asthma diagnoses in treatment-naive patients without prior obstruction documented.