OSCILLOMETRY HOME-MONITORING CAN PREDICT PULMONARY EXACERBATIONS IN CHILDREN WITH CYSTIC FIBROSIS

Abstract

Introduction/Aim: Variability in lung function when 'clinically stable' is recognised as a significant risk factor for subsequent pulmonary exacerbation (PEx) and future lung function decline in cystic fibrosis (CF). Conventional lung function testing (i.e., spirometry) is insensitive in detecting early changes of PEx. We used an -8-week oscillometry (OSC) homemonitoring program to explore the ability of OSC indices to predict PEx onset in children with CF. Method: Thirteen children (7 female, mean ± SD 9.3 ± 2.0 years-old) completed daily OSC measurements (tremoflo-C2, Thorasys, Canada) and respiratory symptom questionnaires. Day-to-day variability of resistance (R) and reactance (X) was calculated as standard deviation (SD) over 7-/6-/5-day running windows. Baseline data was defined using an asymptomatic 7-day window 14-days prior to PEx onset. PEx was defined as presence of respiratory symptoms for 2 consecutive days. Mixed-effect linear regressions compared each day against the baseline period up-to PEx onset. Receiver-operator characteristic (ROC) analysis assessed sensitivity and specificity of OSC indices to predict PEx onset. Results: Ten PEx episodes were identified in 7 children. Changes in dayto- day variability of X5 SD during a 5-day rolling window was most sensitive in detecting changes prior to PEx onset. Mean differences±SE between baseline period and 3-days (0.099 (0.061)), 2-days (0.098 (0.061)) and 1-day (0.145 (0.061)) prior to PEx onset were statistically significant (all p < 0.04). ROC analysis identified X5 SD of 0.40 as the best predictor 3-days prior to PEx onset (AUC = 0.75, sensitivity 70%, specificity 89%). Conclusion: Home-monitoring using OSC may provide an early signal to predict PEx episodes in patients with CF. Changes in OSC indices, particular X5 SD, were noted up to 3-days before PEx onset, potentially creating a window for early intervention. Future work will be performed in larger cohorts and with younger patients to explore this application of OSC further.