Abstract
Background: In health, a physiologically relevant change in the lung clearance index (LCI) exceeds ±15%; in children with cystic fibrosis (CF), the threshold of reproducibility is higher (Stanojevic et al, ERJ, 2021). It is uncertain whether the LCI is intrinsically more variable in CF or if LCI changes outside ±15% are clinically relevant.
Methods: Within a prospective observational study in school-age children with CF (98 subjects) and healthy controls (48 subjects), LCI, FEV1 and CFQ-R Respiratory scores were measured every 3-months over 2-years. Visits associated with a ±15% LCI change were reviewed in detail by two investigators to distinguish intrinsic test variability from changes in respiratory status. An LCI change was categorized as “signal” if the change was consistent with changes in clinical symptoms and/or FEV1, “noise” if there was no change in clinical status or “uncertain” if there was inconsistent or missing clinical information.
Results: LCI changed by at least 15% in 25.6% (n=187) of CF visits (n=731), 78.2% (n=147) were categorized as “signal”, reflecting a clinically relevant improvement (n=56) or worsening (n=91) in a subject’s respiratory status. 11.2% (n=21) and 10.2% (n=19) of LCI changes were categorized as “noise” and of “uncertain” significance, respectively. 4.5% (n=13) of healthy control visits (n=292) were associated with a 15% LCI change, of which 4 reflected improvement (n=2) or worsening (n=2) in respiratory symptoms.
Conclusion: Most LCI changes exceeding 15% reflect clinically relevant changes in CF; LCI could be used to guide treatment decisions where respiratory symptoms are subtle and clinical uncertainty exists.
Funded by CFF and CF Canada
Footnotes
Cite this article as: European Respiratory Journal 2021; 58: Suppl. 65, OA2672.
This abstract was presented at the 2021 ERS International Congress, in session “Prediction of exacerbations in patients with COPD”.
This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only).
- Copyright ©the authors 2021