Predicting clinical exacerbations using respiratory oscillometry during home telemonitoring of patients taking medium-/high-dose asthma treatment

Rationale Strategies for asthma management need better tools to identify risk of exacerbations. In this prospective observational study, we investigated day-to-day variability of lung mechanics, measured using home telemonitored oscillometry, by examining relationships between current symptom control and future risk of exacerbation in asthma patients taking medium-/high-dose treatment, regardless of their level of asthma control. Methods Participants underwent ≥24 weeks of telemonitoring during stable or stepped-down treatment, with once-daily self-recording of symptoms, and oscillometry (Resmon Pro Diary, Restech Srl, Milan, Italy). The 5-item Asthma Control Questionnaire and exacerbations were captured via weekly telephone calls. Mean inspiratory resistance and reactance at 5 Hz (R insp and X insp ), and their standard deviation and coefficient of variation over 7-day windows, were calculated; their associations with current symptom control were examined using linear mixed modelling, and their capacity to predict exacerbations in the following week was examined using logistic regression and receiver-operator characteristic (ROC) analysis, and conditional probability methods. Results Data from 30 participants were analysed (19 female; mean± sd age 59±13 years, body mass index 30.1±6.6 kg·m -2 , percent predicted forced expiratory volume in 1 s 73.7±25.0), with mean monitoring adherence of 83.9±13.1%, and with 16 exacerbations recorded from 12 participants. Only X insp was a significant predictor of current symptom control (p<0.001). Coefficient of variation of inspiratory resistance was the most accurate in predicting future exacerbations (area under the ROC curve (AUC)=0.664, p<0.001); accuracy was further enhanced using individual conditional probability (AUC=0.836, p<0.001). Conclusion This proof-of-concept study shows that daily telemonitoring of oscillometry is useful for assessing current symptom control and future risk of exacerbations in asthma patients taking medium-/high-dose treatment.