Predicting clinical exacerbations using respiratory oscillometry during home telemonitoring of patients taking...

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.

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.

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).

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.