Impact of a Digital Inhalation Coach on Inhalation Errors and Asthma Control

<b><i>Background:</i></b> Inhalation errors are a common source of underdosing in asthma therapy, leading to poor asthma control. Therefore, regular inhalation training is recommended. The Kata® app is a digital inhalation coach that provides step-by-step guidance on how to inhale effectively. This analysis evaluated the effect of the app on inhalation technique and clinical endpoints (fractional exhaled nitric oxide [FeNO]; Asthma Control Questionnaire [ACQ-5]) in a clinical trial. <b><i>Methods:</i></b> This <i>post hoc</i> analysis of app data collected during a phase-II randomized controlled trial, included adult patients with moderate-to-severe, uncontrolled type-2 high asthma (<i>N</i> = 78). A smartphone with the study-specific app version was provided and patients' usual asthma maintenance treatment entered. Inhalations were video recorded whenever the inhalation coach was used. Inhalation errors were scored by trained experts according to predefined criteria. Rates for total and critical errors (significantly affecting drug delivery) were calculated as the number of errors per inhalation. Analysis of clinical endpoints used data from the run-in phase only to avoid interference with study interventions. <b><i>Results:</i></b> Univariate regression analysis showed a significant decrease of the total error rate of 1.4% per study day (<i>p</i> < 0.001; 95% CI: 0.8-1.9) and of the critical error rate (1.8% per study day; <i>p</i> < 0.001; 95% CI: 1.0-2.6). A significant reduction of the ACQ-5 score was found for the run-in phase (<i>p</i> = 0.036; <i>N</i> = 59). The mean (SD) ACQ-5 change (V2-V0) was -0.2 (0.7), reflecting a small improvement of asthma control. A clinically relevant improvement of the ACQ-5 score was found in 18 of 59 patients (31%). No significant improvement of FeNO was found (<i>p</i> = 0.170; <i>N</i> = 60). However, 26 of 60 patients (43%) showed a clinically relevant decrease (>20%) of FeNO. <b><i>Conclusions:</i></b> The Kata app improved inhalation technique and this was accompanied by a small improvement of asthma control. The Kata app is a useful tool for patients using inhalers to treat their asthma.