Perrem, LucyStanojevic, SanjaShaw, MichelleJensen, ReneeMcDonald, NancyIsaac, Sarah M.Davis, MiriamClem, CharlesGuido, JuliaJara, SylviaFrance, LisaSoloman, MelindaGrasemann, HartmutWaters, ValerieSweezey, NeilSanders, Don B.Davis, Stephanie D.Ratjen, Felix2022-04-152022-04-152021-04Perrem, L., Stanojevic, S., Shaw, M., Jensen, R., McDonald, N., Isaac, S. M., Davis, M., Clem, C., Guido, J., Jara, S., France, L., Solomon, M., Grasemann, H., Waters, V., Sweezey, N., Sanders, D. B., Davis, S. D., & Ratjen, F. (2021). Lung Clearance Index to Track Acute Respiratory Events in School-Age Children with Cystic Fibrosis. American Journal of Respiratory and Critical Care Medicine, 203(8), 977–986. https://doi.org/10.1164/rccm.202006-2433OChttps://hdl.handle.net/1805/28493Rationale: The lung clearance index (LCI) is responsive to acute respiratory events in preschool children with cystic fibrosis (CF), but its utility to identify and manage these events in school-age children with CF is not well defined. Objectives: To describe changes in LCI with acute respiratory events in school-age children with CF. Methods: In a multisite prospective observational study, the LCI and FEV1 were measured quarterly and during acute respiratory events. Linear regression was used to compare relative changes in LCI and FEV1% predicted at acute respiratory events. Logistic regression was used to compare the odds of a significant worsening in LCI and FEV1% predicted at acute respiratory events. Generalized estimating equation models were used to account for repeated events in the same subject. Measurements and Main Results: A total of 98 children with CF were followed for 2 years. There were 265 acute respiratory events. Relative to a stable baseline measure, LCI (+8.9%; 95% confidence interval, 6.5 to 11.3) and FEV1% predicted (−6.6%; 95% confidence interval, −8.3 to −5.0) worsened with acute respiratory events. A greater proportion of events had a worsening in LCI compared with a decline in FEV1% predicted (41.7% vs. 30.0%; P = 0.012); 53.9% of events were associated with worsening in LCI or FEV1. Neither LCI nor FEV1 recovered to baseline values at the next follow-up visit. Conclusions: In school-age children with CF, the LCI is a sensitive measure to assess lung function worsening with acute respiratory events and incomplete recovery at follow-up. In combination, the LCI and FEV1 capture a higher proportion of events with functional impairment.enPublisher Policypulmonary exacerbationsmultiple breath washoutlung function recoveryArticle