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Background: The limits of reproducibility of the lung clearance index (LCI) are higher in children with cystic fibrosis (CF) compared with healthy children, and it is currently unclear what defines a clinically meaningful change., Methods: In a prospective multisite observational study of children with CF and healthy controls (HCs), we measured LCI, FEV 1 % predicted and symptom scores at quarterly visits over 2 years. Two reviewers performed a detailed review of visits to evaluate the frequency that between visit LCI changes outside ±10%, ±15%, ±20% represented a clinically relevant signal. In the setting of acute respiratory symptoms, we used a generalised estimating equation model, with a logit link function to determine the ability of LCI worsening at different thresholds to predict failure of lung function recovery at follow-up., Results: Clinically relevant LCI changes outside ±10%, ±15% and ±20% were observed at 25.7%, 15.0% and 8.3% of CF visits (n=744), respectively. The proportions of LCI changes categorised as noise, reflecting biological variability, were comparable between CF and HC at the 10% (CF 9.9% vs HC 13.0%), 15% (CF 4.3% vs HC 3.1%) and 20% (CF 2.4% vs HC 1.0%) thresholds. Compared with symptomatic CF visits without a worsening in LCI, events with ≥10% LCI increase were more likely to fail to recover baseline LCI at follow-up., Conclusion: The limits of reproducibility of the LCI in healthy children can be used to detect clinically relevant changes and thus inform clinical care in children with CF., Competing Interests: Competing interests: SS reports grants from Cystic Fibrosis Canada and US Cystic Fibrosis Foundation, during the conduct of the study. MS reports grants from Vertex Pharmaceutical and Mylene Pharmaceutical, payment for educational module from Vertex Pharamaceutical, outside the submitted work. FR reports grants and personal fees for consultancy from Vertex, Proteostasis, Genentech, Bayer, Novartis and Roche outside the submitted work. The other authors have nothing to disclose., (© Author(s) (or their employer(s)) 2023. No commercial re-use. See rights and permissions. Published by BMJ.)

Structural and functional defects within the lungs of children with cystic fibrosis (CF) are detectable soon after birth and progress throughout preschool years often without overt clinical signs or symptoms. By school age, most children have structural changes such as bronchiectasis or gas trapping/hypoperfusion and lung function abnormalities that persist into later life. Despite improved survival, gains in forced expiratory volume in one second (FEV 1 ) achieved across successive birth cohorts during childhood have plateaued, and rates of FEV 1 decline in adolescence and adulthood have not slowed. This suggests that interventions aimed at preventing lung disease should be targeted to mild disease and commence in early life. Spirometry-based classifications of 'normal' (FEV 1 ≥90% predicted) and 'mild lung disease' (FEV 1 70%-89% predicted) are inappropriate, given the failure of spirometry to detect significant structural or functional abnormalities shown by more sensitive imaging and lung function techniques. The state and readiness of two imaging (CT and MRI) and two functional (multiple breath washout and oscillometry) tools for the detection and monitoring of early lung disease in children and adults with CF are discussed in this article.Prospective research programmes and technological advances in these techniques mean that well-designed interventional trials in early lung disease, particularly in young children and infants, are possible. Age appropriate, randomised controlled trials are critical to determine the safety, efficacy and best use of new therapies in young children. Regulatory bodies continue to approve medications in young children based on safety data alone and extrapolation of efficacy results from older age groups. Harnessing the complementary information from structural and functional tools, with measures of inflammation and infection, will significantly advance our understanding of early CF lung disease pathophysiology and responses to therapy. Defining clinical utility for these novel techniques will require effective collaboration across multiple disciplines to address important remaining research questions. Future impact on existing management burden for patients with CF and their family must be considered, assessed and minimised.To address the possible role of these techniques in early lung disease, a meeting of international leaders and experts in the field was convened in August 2019 at the Australiasian Cystic Fibrosis Conference. The meeting entitiled 'Shaping imaging and functional testing for early disease detection of lung disease in Cystic Fibrosis', was attended by representatives across the range of disciplines involved in modern CF care. This document summarises the proceedings, key priorities and important research questions highlighted., Competing Interests: Competing interests: TR reports personal fees from Vertex Pharmaceuticals during the conduct of the study; in addition, TR has a patent PCT/AU2016/000079 issued. JCD reports others from Algipharma AS, Bayer AG, Boehringer Ingelheim Pharma GmbH & Co. KG, Galapagos NV, ImevaX GmbH, Nivalis Therapeutics, Inc., ProQR Therapeutics III B.V., Proteostasis Therapeutics, Inc., Raptor Pharmaceuticals, Inc, Vertex Pharmaceuticals (Europe) Limited, Enterprise, Novartis, Pulmocide and Flatley; grants from CF Trust; and others from Teva, outside the submitted work. JSE reports grants from Ionis and the European Commission; personal fees and others from Vertex, during the conduct of the study. MM reports grants from the German Federal Ministry of Education and Research and Einstein Foundation Berlin, during the conduct of the study; personal fees and others from Boehringer Ingelheim and Vertex Pharmaceuticals; personal fees from Arrowhead Pharmaceuticals, Santhera, Galapagos, Sterna Biologicals, Enterprise Therapeutics and Antabio, outside the submitted work. FR reports non-financial support from Vertex during the conduct of the study and acts as a consultant to Vertex Pharmaceuticals, who was the sponsor of this meeting. ARS reports grants from Vertex and personal fees from Novartis, Teva and Vertex, outside the submitted work; and patent issued: 'Alkyl quinolones as biomarkers of Pseudomonas aeruginosa infection and uses thereof'. SS reports a patent licensed to Thirona, and a patent licensed to Resonance Health Ltd and Institutional reimbursement from Vertex Pharmaceuticals (Australia) Pty Ltd. for Steering Committee Member duties organising SHIFT at the Australasian Cystic Fibrosis Conference 2019, Perth. CEW reports institutional reimbursement from Vertex Pharmaceuticals (Australia) P/L for Steering Committee Member duties organising SHIFT at the Australasian Cystic Fibrosis Conference 2019, Perth; income on a per patient basis derived from Pharmaceutical Studies - Vertex Pharmaceuticals Inc., and Boehringer-Ingelheim; research grant from Novo Nordisk Pharmaceuticals P/L- CF-IDEA Study; other reimbursements from Vertex Pharmaceuticals P/L honorarium to attend CF International Advisory Board Meeting in February 2014, Vertex Pharmaceuticals P/L honorarium to attend CF Medical Advisory Board Meeting in Adelaide in April 2014, Novartis Pharmaceuticals P/L honorarium to present symposium at National Pediatric Congress in Lebanon in May 2014, European CF Conference in Gothenburg June 2014 Vertex Pharmaceuticals P/L return travel and honorarium for lecture and discussions, North American CF Conference Georgia October 2014 DKBmed, LLC honorarium to present symposium, Vertex Pharmaceuticals P/L honorarium to present as speaker in an educational meeting series in Brisbane and Sydney in April 2015, Vertex Pharmaceuticals P/L honorarium to attend the Vertex Steering Committee Meetings re VX15-770-123 Study in 2014, Vertex Pharmaceuticals P/L honorarium for Vertex Medical Advisory Board- Innovative endpoints in CF in August 2015, The University of Miami honorarium for meeting attendance in 2015, Thorax honorarium for associate editor duties Q3/Q4 2015, BMJ honorarium for work as reviewer, Vertex Pharmaceuticals 2015 Chicago return flight and accommodation as investigator in Lumacaftor study, Vertex Pharmaceuticals 2015–2017 honorarium as speaker at Vertex sponsored educational meeting series in Australia, Vertex Pharmaceuticals 2016 Phoenix return flight and accommodation as investigator in Next Gen study, Vertex Pharmaceuticals December 2016 honoraria as speaker at Vertex sponsored educational meeting in Liverpool, UK DKBmed eCF Review Issue honoraria in January 2017, Vertex Pharmaceuticals–March 2017 honoraria as speaker at TSANZ meeting Vertex Pharmaceuticals Inc. 2014–2018, honorarium for acting as consultant on the Vertex Orkambi 6-11 HTA Advisory Board, the Global Pediatric Advisory Committee, the Global Medical Advisory Board, and the VIA Grants Committee; Gilead Sciences Ltd. honorarium for meeting attendance on CF imaging; Honorarium for In Vivo Academy Limited for webcast meeting attendance at ECFC–2018; Vertex Pharmaceuticals P/L honorarium to present as speaker in an educational meeting at ECFC in Belgrade–2018; Vertex Pharmaceuticals Inc. honorarium to attend Next Gen Early Lifecycle Management Plan–London–2018; Vertex Pharmaceuticals P/L to act as consultant and to render such services in the form of documents, advice, meetings and conferences during the period October 2018; present Vertex Pharmaceuticals P/L to attend the EU Real World Evidence Steering Committee in Amsterdam–2019 Current Board Positions–International Advisory Board Vertex Pharmaceuticals P/L Deputy Editor Thorax /Associate Editor Respirology. PDR reports institutional reimbursement from Vertex Pharmaceuticals (Australia) Pty. Ltd for Steering Committee Member duties organising SHIFT at the Australasian Cystic Fibrosis Conference 2019, Perth., (© Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Current reproducibility standards for spirometry were derived using a small adult dataset and may not be optimal for interpretation of repeated measurements of lung function in children., Objective: To define reproducibility limits for forced expiratory volume in 1 s (FEV 1 ) change that represent the normal within-subject between-visit variability in healthy children and evaluate these limits as a tool to monitor children with cystic fibrosis (CF)., Methods: Repeated FEV 1 measurements (3 months to 5 years apart) from healthy children from the Global Lung Function Initiative data repository were used to derive a conditional change score. Spirometry and clinical data from a CF clinical database was used to verify utility in clinical practice., Results: A reproducibility change score was derived from 47 938 FEV 1 measures from 7885 healthy children 6-18 years of age. The simple algorithm, which is conditional on the initial measurement, also accounts for age and time interval between measurements. The change score limits of reproducibility were much narrower than currently used cut-offs. Specifically, changes, considered as improvements using either a 12% or 10% relative change from baseline, are too wide for children. In CF, there was overall agreement between different approaches, with the distinct advantage that the change score was not biased by regression to the mean., Conclusions: Compared with current approaches to interpretation of repeated lung function measurements, the proposed change score was less biased and provides a simple alternative to reduce misinterpretation., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: The care of infants with recurrent wheezing relies largely on clinical assessment. The lung clearance index (LCI), a measure of ventilation inhomogeneity, is a sensitive marker of early airway disease in children with cystic fibrosis, but its utility has not been explored in infants with recurrent wheezing., Objective: To assess ventilation inhomogeneity using LCI among infants with a history of recurrent wheezing compared with healthy controls., Methods: This is a case-control study, including 37 infants with recurrent wheezing recruited from outpatient clinics, and 113 healthy infants from a longitudinal birth cohort, the Canadian Healthy Infant Longitudinal Development study. All infants, at a time of clinical stability, underwent functional assessment including multiple breath washout, forced expiratory flows and body plethysmography., Results: LCI z-score values among infants with recurrent wheeze were 0.84 units (95% CI 0.41 to 1.26) higher than healthy infants (mean (95% CI): 0.26 (-0.11 to 0.63) vs -0.58 (-0.79 to 0.36), p<0.001)). Nineteen percent of recurrently wheezing infants had LCI values that were above the upper limit of normal (>1.64 z-scores). Elevated exhaled nitric oxide, but not symptoms, was associated with abnormal LCI values in infants with recurrent wheeze (p=0.05)., Conclusions: Ventilation inhomogeneity is present in clinically stable infants with recurrent wheezing., Competing Interests: Competing interests: None declared., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Background: Antibiotic treatment for pulmonary symptoms in preschool children with cystic fibrosis (CF) varies among clinicians. The lung clearance index (LCI) is sensitive to early CF lung disease, but its utility to monitor pulmonary exacerbations in young children has not been assessed., Objective: We aim to (1) understand how LCI changes during lower respiratory tract symptoms relative to a recent clinically stable measurement, (2) determine whether LCI can identify antibiotic treatment response and (3) compare LCI changes to changes in spirometric indices., Methods: LCI and spirometry were measured at quarterly clinic visits over a 12-month period in preschool children with CF. Symptomatic visits were identified and classified as treated or untreated. Treatment response was estimated using propensity score matching methods., Results: 104 symptomatic visits were identified in 78 participants. LCI increased from baseline in both treated (mean relative change +23.8% (95% CI 16.2 to 31.4)) and untreated symptomatic visits (mean relative change +11.2% (95% CI 2.4 to 19.9)). A significant antibiotic treatment effect was observed when LCI was used as the outcome measure (average treatment effect -15.5% (95% CI -25.4 to -5.6)) but not for z-score FEV 1 ., Conclusion: LCI significantly deteriorated with pulmonary symptoms relative to baseline and improved with antibiotic treatment. These data suggest that LCI may have a role in the routine clinical care of preschool children with CF., Competing Interests: Competing interests: None declared., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Background: Despite extensive knowledge regarding the effect of pulmonary exacerbations treated with intravenous antibiotics on clinical outcomes in cystic fibrosis (CF), there is little known about the role of milder pulmonary exacerbations treated with oral antibiotics (oPEx)., Methods: This was a retrospective cohort study of patients with CF followed at the Hospital for Sick Children and St. Michael's Hospital from 2009 to 2014. We evaluated the effect of oPEx on short-term clinical outcomes as the proportion of oPEx events in which 100% or 90% of baseline FEV 1 % predicted was recovered at the end of treatment. We then examined the association of the number of oPEx events in the past 12 months on lung function (FEV 1 % predicted) and nutritional status (body mass index (BMI) z-score) using a mixed-effects model., Results: There were a total of 2608 oPEx events in 570 subjects during the study period. In over half (53.4%) of oPEx events, lung function was already at 90% or higher of baseline FEV 1 at the initiation of oral antibiotic therapy and 82% were at 90% or higher of baseline FEV 1 at follow-up. In individuals with CF, one or more oPex events in the previous 12 months were associated with decreased FEV 1 compared with 12 months periods without oPex events. When the cumulative effect of oPExs on lung function was examined over the entire study period, patients with six or more oPEx events had the steepest rate of FEV 1 decline. oPEx events were not associated with changes in BMI., Conclusions: oPEx events are associated with short-term loss of FEV 1 and have a negative effect on lung function over time., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.)

Background: Positive expiratory pressure (PEP) is the most commonly used method of airway clearance (AC) in Canada for patients with cystic fibrosis (CF) whereas, in some countries, high frequency chest wall oscillation (HFCWO) is the preferred form of AC. There have been no long-term studies comparing the efficacy of HFCWO and PEP in the CF population., Objectives: To determine the long-term efficacy of HFCWO compared with PEP mask therapy in the treatment of CF as measured by the number of pulmonary exacerbations (PEs)., Methods: A randomised controlled study was performed in 12 CF centres in Canada. After a 2-month washout period, subjects were randomised to perform either HFCWO or PEP mask therapy for 1 year., Results: 107 subjects were enrolled in the study; 51 were randomised to PEP and 56 to HFCWO. There were 19 dropouts within the study period, of which 16 occurred prior to or at the time of randomisation. There were significant differences between the groups in the mean number of PEs (1.14 for PEP vs 2.0 for HFCWO) and time to first PE (220 days for PEP vs 115 days for HFCWO, p=0.02). There was no significant difference in lung function, health-related quality of life scores or patient satisfaction scores between the two groups. PEP mask therapy required a shorter treatment time., Conclusions: The results of this study favour PEP and do not support the use of HFCWO as the primary form of AC in patients with CF., Clinical Trial Registration Number: NCT00817180.

BACKGROUND AND AIMS Sensitive outcome measures to assess the efficacy of therapeutic interventions in patients with cystic fibrosis (CF) with mild lung disease are currently lacking. Our objective was to study the ability of the lung clearance index (LCI), a measure of ventilation inhomogeneity, to detect a treatment response to hypertonic saline inhalation in paediatric patients with CF with normal spirometry. METHODS In a crossover trial, 20 patients with CF received 4 weeks of hypertonic saline (HS) and isotonic saline (IS) in a randomised sequence separated by a 4 week washout period. The primary end point was the change in the LCI due to HS versus IS. RESULTS Baseline characteristics including the LCI were not significantly different between both study periods. Four weeks of twice-daily HS inhalation significantly improved the LCI compared with IS (1.16, 95% CI 0.26 to 2.05; p=0.016), whereas other outcome measures such as spirometry and quality of life failed to reach statistical significance. Randomisation order had no significant impact on the treatment effect. CONCLUSIONS The LCI, but not spirometry was able to detect a treatment effect from HS inhalation in patients with CF with mild disease and may be a suitable tool to assess early intervention strategies in this patient population. Clinical trial number NCT00635141.

Rationale: Antibiotic therapy for early Pseudomonas aeruginosa infection in patients with cystic fibrosis (CF) is effective, but the optimal therapeutic regimen and duration for early treatment remains unclear. The EarLy Inhaled Tobramycin for Eradication (ELITE) study was designed to assess the efficacy and safety of two regimens (28 and 56 days) of tobramycin inhalation solution (TIS) 300 mg/5 ml twice daily for the treatment of early onset P aeruginosa infection in patients with CF., Methods: In this open-label randomised multicentre study, patients with CF (aged > or = 6 months) with early P aeruginosa infection were treated for 28 days with TIS twice daily administered by the PARI LC PLUS (PARI GmbH, Starnberg, Germany) jet nebuliser. After 28 days, patients were randomised 1:1 to either stop TIS (n=45) or to receive a further 28 days of TIS (n=43). The primary endpoint was the median time to recurrence of P aeruginosa (any strain). Secondary endpoints included the proportion of patients free of P aeruginosa infection 1 month after cessation of therapy and safety assessments., Results: The median time to recurrence of P aeruginosa (any strain) was similar between the two groups. In total, 93% and 92% of the patients were free of P aeruginosa infection 1 month after the end of treatment and 66% and 69% remained free at the final visit in the 28-day and 56-day groups, respectively. TIS was well tolerated., Conclusions: Treatment with TIS for 28 days is an effective and well tolerated therapy for early P aeruginosa infection in patients with CF., Trial Registration Number: NCT00391976.

Background: Matrix metalloproteinases (MMPs) are involved in the remodelling and degradation of extracellular matrix and may play a role in pulmonary tissue destruction in cystic fibrosis (CF)., Methods: Bronchoalveolar lavage (BAL) fluid levels of MMP-8, MMP-9, and their natural inhibitor TIMP-1 were measured on two occasions within 18 months in 23 children with mild CF, 13 of whom were treated with DNase., Results: MMP-8 (39.3 (6.8) v 0.12 (0.01) ng/ml), MMP-9 (58.0 (11.4) v 0.5 (0.02) ng/ml), and the molar ratio of MMP-9/TIMP-1 (0.36 (0.05) v 0.048 (0.01)) were significantly higher in patients with CF than in control children without lung disease. Gelatine zymography showed the typical banding pattern of neutrophil derived MMP-9, including 130 kDa NGAL-MMP-9 complex and 92 kDa latent MMP-9 bands; 85 kDa bands (corresponding to active MMP-9) were seen in all patients. There was a close correlation between BAL fluid concentrations of MMPs and alpha(2)-macroglobulin, a marker of alveolocapillary leakage. After 18 months MMP levels were increased in untreated patients and decreased in patients treated with DNase., Conclusions: Uninhibited MMPs may contribute to pulmonary tissue destruction even in CF patients with mild lung disease that may be positively affected by treatment with DNase.

Background: Pulmonary infections are associated with an increase in capillary permeability but information regarding age related differences in the local inflammatory response is lacking. To quantify the degree of capillary leakage during inflammation, the concentrations of the plasma proteins albumin, alpha1-antitrypsin, alpha2-macroglobulin and the locally produced proteins elastase, myeloperoxidase, lactoferrin and fibronectin were studied in the bronchoalveolar lavage (BAL) fluid of immunosuppressed children and adults with pneumonia., Methods: Sixteen children aged 2-16 years and 15 adults who developed pneumonia while receiving immunosuppressive therapy for haematological malignancies were included in the study. Bronchoalveolar lavage was performed via a flexible bronchoscope with three aliquots of 1 ml/kg body weight in children and 200 ml in adults. Protein concentrations in BAL fluid were determined using highly sensitive immunoluminometric assays., Results: Despite considerable variability, the median concentrations of all proteins in BAL fluid were significantly higher in both patient populations than in previously collected age adjusted reference values. The concentrations of serum derived proteins were significantly higher in children with pneumonia than in adult patients. In contrast, no differences were observed between the two groups for locally produced proteins., Conclusions: These data suggest that the degree of protein exudation is more pronounced in immunosuppressed children with pneumonia than in adults in a similar clinical situation. This is in agreement with our studies in healthy individuals and may reflect a greater permeability of the alveolar-capillary membrane in children, regardless of disease status.