Inadequate reduction of inflammation during an exacerbation is associated with failure to recover lung function and increased risk of subsequent re-exacerbation in CF patients.

Pulmonary exacerbations are important clinical events for cystic fibrosis (CF) patients. Studies assessing the ability of the lung clearance index (LCI) to detect treatment response for pulmonary exacerbations have yielded heterogeneous results. Here, we conduct a retrospective analysis of pooled LCI data to assess treatment with intravenous antibiotics for pulmonary exacerbations and to understand factors explaining the heterogeneous response.A systematic literature search was performed to identify prospective observational studies. Factors predicting the relative change in LCI and spirometry were evaluated while adjusting for within-study clustering.Six previously reported studies and one unpublished study, which included 176 pulmonary exacerbations in both paediatric and adult patients, were included. Overall, LCI significantly decreased by 0.40 units (95% CI −0.60-−0.19, p=0.004) or 2.5% following treatment. The relative change in LCI was significantly correlated with the relative change in forced expiratory volume in 1 s (FEV1), but results were discordant in 42.5% of subjects (80 out of 188). Higher (worse) baseline LCI was associated with a greater improvement in LCI (slope: −0.9%, 95% CI −1.0-−0.4%).LCI response to therapy for pulmonary exacerbations is heterogeneous in CF patients; the overall effect size is small and results are often discordant with FEV1. @ERSpublications Lung clearance index response to therapy for pulmonary exacerbations is heterogeneous in cystic fibrosis patients http://ow.ly/Mnvtd

This study highlights that in the treatment of pulmonary exacerbations, maximum lung function is not achieved within 14 days in all patients, and that there is continued improvement beyond this period.