Progression of Lung Disease in Preschool Patients with Cystic Fibrosis

Infant Lung Function in Cystic Fibrosis: A Real-World Study

BACKGROUND

Previous research showed that lung function abnormalities are common in infants with cystic fibrosis (IwCF) but real-world data are missing.

METHODS

This single-center retrospective study analyzed infant lung function results from IwCF born in 2012-2018. The tests were conducted at Great Ormond Street Hospital, London, as part of routine care at 3 months, 1 year, and 2 years of age. Z-scores for SF6 Lung Clearance Index (zLCI), plethysmographic FRC (zFRCpleth) and FEV0.5 were derived. Microbiology and antibiotics prescription from 3 months before lung function assessments, up to the closest medical review following the lung function encounter, were analyzed, along with changes in management advised by the physician.

RESULTS

A total of 126 lung function encounters (n = 43 at 3 months, 46 at 1 year, 37 at 2 years) from 60 IwCF were included. LCI was abnormal (zLCI > 1.96) in 31% (12/39) of 3-month-olds (mean± zLCI 1.21 ± 1.08), 28% (12/43) of 1-year-olds and 19% (7/36) of 2-year-olds (mean± zLCI 1.13 ± 1.10). Among 74 cases with recent positive microbiology or abnormal chest findings at medical review, 100% (31/31) of those with abnormal lung function and 86% (37/43) of those with normal lung function (p = 0.04) had a recent antibiotic prescription or a change in clinical management. Conversely, in encounters with abnormal lung function but normal clinical findings, management changes occurred in only 12% (2/16) of cases.

CONCLUSION

In this real-word cohort of IwCF, clinical management was mainly influenced by clinical findings and only marginally by abnormal lung function (elevated FRC or LCI).

The Frequency and Potential Implications of HFE Genetic Variants in Children With Cystic Fibrosis

BACKGROUND

Genetic modifiers have been identified that increase the risks of lung disease and other complications, such as diabetes in people with cystic fibrosis (CF). Variants in the hemochromatosis gene (HFE) were reported in a study of adults to be associated with worse lung disease.

OBJECTIVES

To ascertain the frequency of HFE variants, particularly C282Y (c.845G > A) and H63D (c.187C > G) and to determine if they are associated with variations in the onset and early severity of CF lung disease as well as abnormalities in iron status.

DESIGN

We studied with whole genome sequencing and clinical outcome measures in a cohort of 104 children with CF at 5-6 years old who were previously found to show an association between aggregated genetic modifiers and an earlier onset and a more severe lung disease phenotype.

RESULTS

In our cohort, 23% have H63D and 11% have C282Y. Lung function at age 6 years and Pseudomonas aeruginosa infections did not differ by HFE variants, but having C282Y was associated with more pulmonary exacerbations in the first 6 years of life. Three patients have H63D/C282Y genotype, and all showed phenotypic expression of hemochromatosis with abnormal iron indices.

CONCLUSION

Our study revealed that the presence of HFE variant C282Y in people with CF may lead to more severe lung disease manifestations beginning in early childhood. There is a risk of hemochromatosis in CF patients with two HFE variants, and thus they should be followed for evidence of iron overload.

Utility and interpretation of multiple breath washout in children with cystic fibrosis

Transformative changes in the health of children with cystic fibrosis (CF) mean that more sensitive outcome measures are needed to monitor paediatric CF lung disease. Multiple breath washout (MBW) and its primary readout lung clearance index are gaining increasing traction as an endpoint for clinical trials in the CF space and show promise as a clinical investigation. In this article, we use four clinically based questions to explore what MBW can and cannot (yet) do and highlight some of its strengths and weaknesses as an investigation. We end by discussing how we can increase the utility of MBW as an investigation in children with CF.

An update on multiple breath washout in children with cystic fibrosis

INTRODUCTION

Cystic fibrosis (CF) is an autosomal recessive disorder caused by mutations in the CF transmembrane regulator (CFTR) gene, leading to progressive lung disease and systemic complications. Lung disease remains the primary cause of morbidity and mortality, making early detection of lung function decline crucial. The Lung Clearance Index (LCI), derived from the multiple breath washout (MBW) test, has emerged as a sensitive measure for identifying early airway disease.

AREAS COVERED

This review examines the technical aspects and clinical relevance of LCI, its advantages over traditional lung function tests, and its application in CF clinical trials. A focused literature review highlights LCI's utility in evaluating treatment efficacy and its potential integration into routine CF care.

EXPERT OPINION

LCI is more sensitive than spirometry for detecting early lung function decline and is predominantly used in pediatric settings. Its use is expanding in adult CF populations as advances in treatment allow adults to maintain stable lung function. In clinical trials, LCI is widely recognized as an outcome measure. While implemented into clinical care in many centers in Europe, this is not yet the case in North America. Faster testing protocols and point-of-care interpretation tools will support LCI's integration into routine CF monitoring.

Development of a Miniaturized Mechanoacoustic Sensor for Continuous, Objective Cough Detection, Characterization and Physiologic Monitoring in Children With Cystic Fibrosis

Cough is an important symptom in children with acute and chronic respiratory disease. Daily cough is common in Cystic Fibrosis (CF) and increased cough is a symptom of pulmonary exacerbation. To date, cough assessment is primarily subjective in clinical practice and research. Attempts to develop objective, automatic cough counting tools have faced reliability issues in noisy environments and practical barriers limiting long-term use. This single-center pilot study evaluated usability, acceptability and performance of a mechanoacoustic sensor (MAS), previously used for cough classification in adults, in 36 children with CF over brief and multi-day periods in four cohorts. Children whose health was at baseline and who had symptoms of pulmonary exacerbation were included. We trained, validated, and deployed custom deep learning algorithms for accurate cough detection and classification from other vocalization or artifacts with an overall area under the receiver-operator characteristic curve (AUROC) of 0.96 and average precision (AP) of 0.93. Child and parent feedback led to a redesign of the MAS towards a smaller, more discreet device acceptable for daily use in children. Additional improvements optimized power efficiency and data management. The MAS's ability to objectively measure cough and other physiologic signals across clinic, hospital, and home settings is demonstrated, particularly aided by an AUROC of 0.97 and AP of 0.96 for motion artifact rejection. Examples of cough frequency and physiologic parameter correlations with participant-reported outcomes and clinical measurements for individual patients are presented. The MAS is a promising tool in objective longitudinal evaluation of cough in children with CF.

Assessing 129Xe multi-breath washout MRI response to elexacaftor/tezacaftor/ivacaftor intervention in pediatric CF

BACKGROUND

Monitoring multiple-breath washout (MBW) of a xenon tracer using magnetic resonance imaging (MBW Xe-MRI) provides quantitative regional measures of gas washout (fractional ventilation, FV) and spatial ventilation heterogeneity (coefficient of variation, CoVFV) in pediatric CF lung disease, but has yet to be evaluated in an interventional setting.

METHODS

12 pediatric CF participants (median age 15.3 ± 2 years) completed MBW Xe-MRI, pulmonary function tests (PFTs) (spirometry, N2 MBW for lung clearance index (LCI)) and single-breath Xe-MRI ventilation defect percent (VDP) measurements at baseline and 1-month post-initiation of elexacaftor/tezacaftor/ivacaftor (ETI) therapy. FV maps were calculated from MBW Xe-MRI washout images, and CoVFV maps were derived from FV maps. Significant changes between visits were determined using a paired Wilcoxon signed-rank test. For correlations between absolute changes, Pearson's correlation was used.

RESULTS

All measures changed significantly 1-month post-ETI therapy compared to baseline. For MRI metrics, median [IQR] VDP was significantly (P < 0.001) lower at 1 month (8.0 [3.7 12.4]) compared to baseline (17.8 [8.3 22.5]), FV was significantly (P < 0.05) higher at 1 month (0.42 [0.41 0.46]) compared to baseline (0.38 [0.33 0.44]), and CoVFV was significantly (P < 0.001) lower at 1 month (0.06 [0.05 0.07]) compared to baseline (0.09 [0.08 0.12]). Both absolute and relative differences in CoVFV and LCI were found to correlate highly (R = 0.92, P < 0.0001 and R = 0.91, P < 0.0001, respectively).

CONCLUSIONS

Functional information derived from MBW Xe-MRI, particularly CoVFV, can be used to assess regional lung function in pediatric CF patients in an interventional setting and may be complementary to VDP and pulmonary function tests.

Impact of elexacaftor/tezacaftor/ivacaftor therapy on lung clearance index and magnetic resonance imaging in children with cystic fibrosis and one or two F508del alleles

BACKGROUND

We recently demonstrated that elexacaftor/tezacaftor/ivacaftor (ETI) improves the lung clearance index (LCI) and abnormalities in lung morphology detected by magnetic resonance imaging (MRI) in adolescent and adult patients with cystic fibrosis (CF). However, real-world data on the effect of ETI on these sensitive outcomes of lung structure and function in school-age children with CF have not been reported. The aim of this study was therefore to examine the effect of ETI on the LCI and the lung MRI score in children aged 6-11 years with CF and one or two F508del alleles.

METHODS

This prospective, observational, multicentre, post-approval study assessed the longitudinal LCI up to 12 months and the lung MRI score before and 3 months after initiation of ETI.

RESULTS

A total of 107 children with CF including 40 heterozygous for F508del and a minimal function mutation (F/MF) and 67 homozygous for F508del (F/F) were enrolled in this study. Treatment with ETI improved the median (interquartile range (IQR)) LCI in F/MF (-1.0 (-2.0- -0.1); p<0.01) and F/F children (-0.8 (-1.9- -0.2); p<0.001) from 3 months onwards. Further, ETI improved the median (IQR) MRI global score in F/MF (-4.0 (-9.0-0.0); p<0.01) and F/F children (-3.5 (-7.3- -0.8); p<0.001).

CONCLUSIONS

ETI improves early abnormalities in lung ventilation and morphology in school-age children with CF and at least one F508del allele in a real-world setting. Our results support early initiation of ETI to reduce or even prevent lung disease progression in school-age children with CF.

Lung Clearance Index as a Screening Parameter of Pulmonary Impairment in Patients under Immune Checkpoint Therapy: A Pilot Study

Background: Immune checkpoint blockade (ICB) has presented a breakthrough in the treatment of malignant tumors and increased the overall survival of patients with various tumor entities. ICB may also cause immune-related adverse events, such as pneumonitis or interstitial lung disease. The lung clearance index (LCI) is a multiple-breath washout technique offering information on lung pathology in addition to conventional spirometry. It measures the degree of pulmonary ventilation inhomogeneity and allows early detection of pulmonary damage, especially that to peripheral airways. Methods: This cross-sectional study compared the lung function of patients with melanoma or metastatic cutaneous squamous cell carcinoma who received programmed cell death 1 (PD-1) and cytotoxic T-Lymphocyte-associated Protein 4 (CTLA-4) antibodies, alone or in combination, to age- and sex-matched controls. Lung function was assessed using spirometry, according to American Thoracic Society and European Respiratory Society standards, the LCI, and a diffusion capacity of carbon monoxide (DLCO) measurement. Results: Sixty-one screened patients and thirty-eight screened controls led to nineteen successfully included pairs. The LCI in the ICB-treated patients was 8.41 ± 1.15 (mean ± SD), which was 0.32 higher compared to 8.07 ± 1.17 in the control group, but the difference was not significant (p = 0.452). The patients receiving their ICB therapy for under five months showed a significantly lower LCI (7.98 ± 0.77) compared to the ICB patients undergoing therapy for over five months (9.63 ± 1.22) at the point of testing (p = 0.014). Spirometric analysis revealed that the forced expiratory volume between 25 and 75% of the forced vital capacity (FEF25-75%) in the ICB-treated patients was significantly reduced (p = 0.047) compared to the control group. DLCO (%predicted and adjusted for hemoglobin) was 94.4 ± 19.7 in the ICB patients and 93.4 ± 21.7 in the control group (p = 0.734). Conclusions: The patients undergoing ICB therapy showed slightly impaired lung function compared to the controls. Longer periods of ICB treatment led to deterioration of the LCI, which may be a sign of a subclinical inflammatory process. The LCI is feasible and may be easily integrated into the clinical daily routine and could contribute to early detection of pulmonary (auto-)inflammation.

Short-term effects of positive expiratory pressure mask on ventilation inhomogeneity in children with cystic fibrosis: A randomized, sham-controlled crossover study

BACKGROUND

Can physiotherapy with a positive expiratory pressure (PEP) mask improve peripheral ventilation inhomogeneity, a typical feature of children with cystic fibrosis (cwCF)? To answer this question, we used the nitrogen multiple-breath washout (N2MBW) test to measure diffusion-convection-dependent inhomogeneity arising within the intracinar compartment (Sacin*VT).

METHODS

For this randomized, sham-controlled crossover trial, two N2MBW tests were performed near the hospital discharge date: one before and the other after PEP mask therapy (1 min of breathing through a flow-dependent PEP device attached to a face mask, followed by three huffs and one cough repeated 10 times) by either a standard (10-15 cmH20) or a sham (<5 cmH20) procedure on two consecutive mornings. Deception entailed misinforming the subjects about the nature of the study; also the N2MBW operators were blinded to treatment allocation. Study outcomes were assessed with mixed-effect models.

RESULTS

The study sample was 19 cwCF (ten girls), aged 11.4 (2.7) years. The adjusted Sacin*VT mean difference between the standard and the sham procedure was -0.015 (90% confidence interval [CI]: -∞ to 0.025) L-1. There was no statistically significant difference in Scond*VT and lung clearance index between the two procedures: -0.005 (95% CI: -0.019 to 0.01) L-1 and 0.49 (95% CI: -0.05 to 1.03) turnovers, respectively.

CONCLUSION

Our findings do not support evidence for an immediate effect of PEP mask physiotherapy on Sacin*VT with pressure range 10-15 cmH20. Measurement with the N2MBW and the crossover design were found to be time-consuming and unsuitable for a short-term study of airway clearance techniques.

Correlation Between Lung Clearance Index (LCI) and Forced Expiratory Volume (FEV1) in Children with Cystic Fibrosis (CF): A Cross-sectional Study

Background: The Lung Clearance Index (LCI) serves as a non-uniform ventilation index utilized for monitoring pulmonary function in patients with cystic fibrosis (CF). Lung Clearance Index exhibits higher sensitivity compared to forced expiratory volume in 1 second (FEV1) for early detection of lung disease and does not necessitate active patient cooperation, as required for FEV1 measured through spirometry. Presently, FEV1 is the standard parameter employed for monitoring lung function in CF patients. Objectives: The objective of this study was to assess the correlation between LCI and FEV1 in patients with cystic fibrosis. Methods: This cross-sectional study enrolled children aged 6 to 18 years with confirmed CF diagnosis, who were referred to the CF clinic at Children's Medical Center Hospital (Tehran, Iran). Participants completed consent forms and subsequently underwent pulmonary function tests. Lung Clearance Index was calculated using the exhaling-D device via the Multiple Breath Washout (MBW) method, followed by FEV1 assessment through spirometry. Results: The study included 52 patients with an average age of 12 years, among whom 52% were males. The mean ± standard deviation of FEV1 and LCI were 80.2% ± 25.3 and 8.9 ± 2.8, respectively. A significant inverse relationship was observed between these two parameters in the study (r = -0.49, P = 0.001). Conclusions: These findings further underscore the potential utility of LCI, which offers ease of administration and demonstrates high reliability and accuracy compared to FEV1 for monitoring pulmonary function in CF patients.

Bronchiolitis hospital admission in infancy is associated with later preschool ventilation inhomogeneity

BACKGROUND

Rhinovirus (RV) positive bronchiolitis episodes in infancy confer a higher risk to develop asthma in later childhood with associated lung function impairments. We aimed to investigate the association between the type of virus causing a bronchiolitis hospitalization episode and lung ventilation inhomogeneities at preschool age.

METHODS

Infants hospitalized with a clinical diagnosis of moderate (ward admission) or severe (pediatric intensive care ward admission) bronchiolitis were prospectively followed-up at preschool age to assess nitrogen (N2 ) multiple breath washout (MBW). Lung clearance index (LCI), functional residual capacity (FRC), and concentration normalized phase III slope analysis (SnIII ) indices were reported from ≥2 technically acceptable trials. Differences between groups were calculated using logistic and linear regression and adjusted for confounders (sex, age at bronchiolitis admission, height at visit, maternal asthma, and doctor-diagnosed asthma, including interaction terms between the latter three). An interaction term was included in a regression model to test for an interaction between RV bronchiolitis severity and MBW parameters at preschool age.

RESULTS

One hundred and thirty-nine subjects attended preschool follow-up, of which 84 out of 103 (82%) performing MBW had technically acceptable data. Children with a history of RV positive bronchiolitis (n = 39) had increased LCI (adjusted β-coefficient [aβ] = 0.33, 95% confidence interval [CI] 0.02-0.65, p = 0.040) and conductive airways ventilation inhomogeneity [Scond ] (aβ = 0.016, CI 0.004-0.028, p = 0.011) when compared with those with a RV negative bronchiolitis history (n = 45). In addition, we found a statistical interaction between RV bronchiolitis and bronchiolitis severity strengthening the association with LCI (aβ = 0.93, CI 0.20-1.58, p = 0.006).

CONCLUSION

Children with a history of hospital admission for RV positive bronchiolitis in infancy might be at a higher risk of lung ventilation inhomogeneities at preschool age, arising from the peripheral conducting airways.

Impact of Reanalysis of Nitrogen Multiple-Breath Washout on its Relationship with Chest Magnetic Resonance Imaging Findings in Clinically Stable and Pulmonary Exacerbated Children with Cystic Fibrosis

RATIONALE

Multiple-breath washout (MBW)-derived lung clearance index (LCI) detects lung disease in children with cystic fibrosis (CF). Correction of a cross-talk error in the software of the MBW device Exhalyzer D in a new software version has generated significant interest regarding its impact on previous MBW findings. Since LCI and chest magnetic resonance imaging (MRI) correlated before in CF children, this study aims to reassess previous MBW data after correction.

PATIENTS/METHODS

Reanalysis of the main findings from a previously published study comparing MBW and MRI in a pediatric CF cohort by reassessment of nitrogen (N2) MBW of 61 stable children with CF, 75 age-matched healthy controls (HC), and 15 CF children with pulmonary exacerbation (PEx) in the corrected software version.

RESULTS

The corrected LCI (N2LCIcor) decreased in the entire cohort (-17.0 (11.2)%), HC (-8.5 (8.2)%), stable CF children (-22.2 (11.1)%), and within the PEx group at baseline, at PEx and after antibiotic therapy (-21.5 (7.3)%; -22.5 (6.1)%; -21.4 (6.6)%; all P<0.01). N2LCIcor and N2LCIpre correlated with chest MRI scores in stable CF (r=0.70 to 0.84; all P<0.01) without a significant difference between N2LCIcor and N2LCIpre. Change in LCI from baseline to PEx and from PEx to after therapy decreased from N2LCIpre to N2LCIcor, but these changes remained significant (all P=0.001).

DISCUSSION/CONCLUSIONS

Our results indicate that N2LCIcor is significantly lower than N2LCIpre, but key results published in the original study demonstrating N2MBW and MRI as complementary methods for clinical surveillance in children with CF remain unaffected.

Reanalysis of N2-lung clearance index and the comparison to SF6-lung clearance index and magnetic resonance imaging

Since the finding and correction of an error in previous spiroware software versions commonly used with the Exhalyzer D for multiple-breath washout (MBW) analysis, there has been an ongoing discussion about its impact on MBW results. In this study, we reanalyzed previously published findings with the corrected spiroware version 3.3.1. In total, 31 infants and preschool children with cystic fibrosis (CF) (mean age 2.3 ± 0.8 years) and 20 healthy controls (mean age 2.3 ± 1.1 years) underwent consecutive sulfure hexafluoride (SF6)- and nitrogen (N2)-MBW. In addition, children with CF underwent chest magnetic resonance imaging (MRI) on the same day. After reanalysis of MBW data, the corrected N2-lung clearance index (LCI) decreased by 10-15% in both groups (P = 0.001) but remained significantly higher than the SF6-LCI (P<0.01). Diagnostic agreement between the MBW results remained moderate with a persistent correlation between SF6- and N2-MBW. The corrected upper limit of normal of the N2-LCI changed classification of nine children with CF, eight of which were within the normal range after correction. The correlation between the different LCI values and the chest MRI scores remained significant with strongest correlation with the MRI perfusion score. Consequently, the corrected N2-LCI is significantly lower than the previous N2-LCI, but key results published before are not affected by the reanalysis.

Impact of intrinsic and extrinsic risk factors on early-onset lung disease in cystic fibrosis

BACKGROUND

Although respiratory pathology is known to develop in young children with cystic fibrosis (CF), the determinants of early-onset lung disease have not been elucidated.

OBJECTIVE

We aimed to determine the impact of potential intrinsic and extrinsic risk factors during the first 3 years of life, testing the hypothesis that both contribute significantly to early-onset CF lung disease.

DESIGN

We studied 104 infants born during 2012-2017, diagnosed through newborn screening by age 3 months, and evaluated comprehensively to 36 months of age. Lung disease manifestations were quantified with a new scoring system known as CFELD for Cystic Fibrosis Early-onset Lung Disease. The variants in the cystic fibrosis transmembrane conductance regulator (CFTR) gene were determined and categorized. Whole genome sequencing was performed on each subject and the data transformed to polygenic risk scores (PRS) that aggregate variants associated with lung function. Extrinsic factors included socioeconomic status (SES) indicators and environmental experiences such as exposures to smoking, pets, and daycare.

RESULTS

We found by univariate analysis that CFTR genotype and genetic modifiers aggregated by the PRS method were significantly associated with early-onset CF lung disease. Ordinal logistic regression analysis demonstrated that high and stable SES (maternal education ≥community college, stable 2-parent home, and not receiving Medicaid) and better growth (weight-for-age and height-for-age z-scores) reduced risks, while exposure to smoking and daycare ≥20 h/week increased the risk of CFELD severity.

CONCLUSIONS

Extrinsic, modifiable determinants are influential early and potentially as important as the intrinsic risk factors in the onset of CF lung disease.

Intra- and Inter-visit Repeatability of 129 Xenon Multiple-Breath Washout MRI in Children With Stable Cystic Fibrosis Lung Disease

BACKGROUND

Multiple-breath washout (MBW) 129 Xe MRI (MBW Xe-MRI) is a promising technique for following pediatric cystic fibrosis (CF) lung disease progression. However, its repeatability in stable CF needs to be established to use it as an outcome measure for novel therapies.

PURPOSE

To assess intravisit and intervisit repeatability of MBW Xe-MRI in healthy and CF children.

STUDY TYPE

Prospective, longitudinal cohort study.

SUBJECTS

A total of 18 pediatric subjects (7 healthy, 11 CF).

FIELD STRENGTH/SEQUENCE

A 3 T/2D coronal hyperpolarized (HP) 129 Xe images using GRE sequence.

ASSESSMENT

All subjects completed MBW Xe-MRI, pulmonary function tests (PFTs) (spirometry, nitrogen [N2 ] MBW for lung clearance index [LCI]) and ventilation defect percent (VDP) at baseline (visit 1) and 1-month after. Fractional ventilation (FV), coefficient of variation (CoVFV ) maps were calculated from MBW Xe-MRI data acquired between intervening air washout breaths performed after an initial xenon breath-hold. Skewness of FV and CoVFV map distributions was also assessed.

STATISTICAL TESTS

Repeatability: intraclass correlation coefficients (ICC), within-subject coefficient of variation (CV%), repeatability coefficient (CR). Agreement: Bland-Altman. For correlations between MBW Xe-MRI, VDP and PFTs: Spearman's correlation. Significance threshold: P < 0.05.

RESULTS

For FV, intravisit median [IQR] ICC was high in both healthy (0.94 [0.48, 0.99]) and CF (0.83 [0.04, 0.97]) subjects. CoVFV also had good intravisit ICC in healthy (0.92 [0.42, 0.99]) and CF (0.79 [0.02, 0.96]) subjects. Similarly, for FV, intervisit ICC was high in health (0.94 [0.68, 0.99]) and CF (0.89 [0.61, 0.97]). CoVFV also had good intervisit ICC in health (0.92 [0.42, 0.99]) and CF (0.78 [0.26, 0.94]). FV had better intervisit repeatability than VDP. CoVFV correlated significantly with LCI (R = 0.56). Skewness of FV distributions significantly distinguished between cohorts at baseline.

DATA CONCLUSION

MBW Xe-MRI had high intravisit and intervisit repeatability in healthy and stable CF subjects. CoVFV correlated with LCI, suggesting the importance of ventilation heterogeneity to early CF.

EVIDENCE LEVEL

1.

TECHNICAL EFFICACY

Stage 2.

Pulmonary Function Tests in the Evaluation of Early Lung Disease in Cystic Fibrosis

BACKGROUND

Properly evaluating respiratory system dysfunction is essential in children with cystic fibrosis (CF). This prospective study aimed to assess the course of early lung disease based on multiple breath nitrogen washout (MBNW), impulse oscillometry (IOS), and conventional techniques, such as spirometry and body plethysmography.

METHODS

Over a 2 year recruitment period, subjects with CF aged 7-18 performed pulmonary function tests (PFTs). Moreover, the nutritional and microbiological status, frequency of pulmonary exacerbations (PExs), and patients' health-related quality of life (HRQoL) were assessed.

RESULTS

The mean age of the children (n = 69) was 14.09 ± 3.26 years; F/M 37/32. Spirometry-based diagnoses of normal lung function (forced expiratory volume in 1 s, FEV₁ ≥ 90%pred), mild (FEV₁ 70-89%pred) and moderate (FEV₁ 40-69%pred) lung diseases were established in 34 (49.3%), 25 (36.2%), and 10 (14.5%) patients, respectively. An elevated lung clearance index (LCI > 6.98) was observed in 85% of the subjects with normal FEV₁. The presence of Pseudomonas aeruginosa infection (n = 16) and the number of PExs treated with IV antibiotics were associated with significantly worse PFT results.

CONCLUSIONS

MBNW and IOS are more helpful tools than conventional techniques in assessing early lung disease in CF. LCI is a more useful parameter for detecting functional abnormalities than FEV₁ in school-age children.

Phase 3 Open-Label Clinical Trial of Elexacaftor/Tezacaftor/Ivacaftor in Children Aged 2-5 Years with Cystic Fibrosis and at Least One F508del Allele

Rationale: Elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) has been shown to be safe and effective in people with cystic fibrosis (CF) aged ⩾6 years with at least one F508del-CFTR allele but has not been studied in younger children. Objectives: To evaluate the safety, pharmacokinetics, pharmacodynamics, and efficacy of ELX/TEZ/IVA in children with CF aged 2-5 years. Methods: In this phase 3, open-label, two-part study (parts A and B), children weighing <14 kg (on Day 1) received ELX 80 mg once daily (qd), TEZ 40 mg qd, and IVA 60 mg each morning and 59.5 mg each evening; children weighing ⩾14 kg received ELX 100 mg qd, TEZ 50 mg qd, and IVA 75 mg every 12 hours. Measurements and Main Results: The primary endpoints for part A (15-d treatment period) were pharmacokinetics and safety and tolerability. For part B (24-wk treatment period), the primary endpoint was safety and tolerability; secondary endpoints included pharmacokinetics and absolute changes from baseline in sweat chloride concentration and lung clearance index2.5 (LCI2.5, defined as the number of lung turnovers required to reduce the end tidal N2 concentration to 2.5% of its starting value) through Week 24. Analysis of pharmacokinetic data from 18 children enrolled in part A confirmed the appropriateness of the part B dosing regimen. In part B, 75 children (F508del/minimal function genotypes, n = 52; F508del/F508del genotype, n = 23) were enrolled and dosed. Seventy-four children (98.7%) had adverse events, which were all mild (62.7%) or moderate (36.0%) in severity. The most common adverse events were cough, fever, and rhinorrhea. Decreases in sweat chloride concentration (-57.9 mmol/L; 95% confidence interval [CI], -61.3 to -54.6; n = 69) and LCI2.5 (-0.83 U; 95% CI, -1.01 to -0.66; n = 50) were observed from baseline through Week 24. Mean body mass index was within the normal range at baseline and remained stable at Week 24. Conclusions: In this open-label study in children 2-5 years of age, ELX/TEZ/IVA treatment was generally safe and well tolerated, with a safety profile consistent with that observed in older age groups, and led to clinically meaningful reductions in sweat chloride concentration and LCI2.5. Clinical trial registered with www.clinicaltrials.gov (NCT04537793).

Evaluation of clinically relevant changes in the lung clearance index in children with cystic fibrosis and healthy controls

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, FEV₁% 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.

TRACK-CF prospective cohort study: Understanding early cystic fibrosis lung disease

Background

Lung disease as major cause for morbidity in patients with cystic fibrosis (CF) starts early in life. Its large phenotypic heterogeneity is partially explained by the genotype but other contributing factors are not well delineated. The close relationship between mucus, inflammation and infection, drives morpho-functional alterations already early in pediatric CF disease, The TRACK-CF cohort has been established to gain insight to disease onset and progression, assessed by lung function testing and imaging to capture morpho-functional changes and to associate these with risk and protective factors, which contribute to the variation of the CF lung disease progression.

Methods and design

TRACK-CF is a prospective, longitudinal, observational cohort study following patients with CF from newborn screening or clinical diagnosis throughout childhood. The study protocol includes monthly telephone interviews, quarterly visits with microbiological sampling and multiple-breath washout and as well as a yearly chest magnetic resonance imaging. A parallel biobank has been set up to enable the translation from the deeply phenotyped cohort to the validation of relevant biomarkers. The main goal is to determine influencing factors by the combined analysis of clinical information and biomaterials. Primary endpoints are the lung clearance index by multiple breath washout and semi-quantitative magnetic resonance imaging scores. The frequency of pulmonary exacerbations, infection with pro-inflammatory pathogens and anthropometric data are defined as secondary endpoints.

Discussion

This extensive cohort includes children after diagnosis with comprehensive monitoring throughout childhood. The unique composition and the use of validated, sensitive methods with the attached biobank bears the potential to decisively advance the understanding of early CF lung disease.

Ethics and trial registration

The study protocol was approved by the Ethics Committees of the University of Heidelberg (approval S-211/2011) and each participating site and is registered at clinicaltrials.gov (NCT02270476).

Impact of antibiotic eradication therapy of Pseudomonas aeruginosa on long term lung function in cystic fibrosis

INTRODUCTION

While antibiotic eradication therapy (AET) of early Pseudomonas aeruginosa infection is considered standard of care, its long-term effect on the subsequent course of cystic fibrosis (CF) lung disease remains unclear.

METHODS

CF patients who were P. aeruginosa-free for at least a year and had a minimum of 10 years of pulmonary function measurements were included. Subjects were categorized as Never if they never had P. aeruginosa isolated from a respiratory tract sample. Subjects changed to the Eradicated group if they had a P. aeruginosa infection, were treated with AET, and subsequently cleared their infection. Subjects changed to the Chronic group if AET did not clear their P. aeruginosa infection. The primary outcome was absolute FEV₁ decline over time, with age as the time variable. Mixed-effects linear regression models were used to account for the repeated lung function measurements over time within each patient.

RESULTS

205 CF subjects (48% female) were included; the median (IQR) age at first infection was 9.6 (5.6, 14.6) years. The median (IQR) follow-up was 10.2 (5.7, 14.7) years for the Eradicated group, 8.8 (4.5, 14.9) years for the Chronic group and 2.8 (1.0, 5.7) years for the Never group was among those patients that had at least one P. aeruginosa infection over the study period, annual lung function decline of FEV₁ was significantly less (-1.11% predicted/year; 95% CI: -1.18, -1.04) in the Eradication group compared to the Chronic group (-1.57%; -1.64, -1.50) (p<0.001).

CONCLUSIONS

AET against P. aeruginosa improves lung function trajectory in CF patients.

Variability of clinically measured lung clearance index in children with cystic fibrosis

RATIONALE

The lung clearance index (LCI) is increasingly being used in the clinical surveillance of patients with cystic fibrosis (CF). However, there are limited data on long-term variability and physiologically relevant changes in LCI during routine clinical surveillance.

OBJECTIVES

To evaluate the long-term variability of LCI and propose a threshold for a physiologically relevant change.

METHODS

In children aged 4-18 years with CF, LCI was measured every 3 months as part of routine clinical surveillance during 2011-2020 in two centers. The variability of LCI during periods of clinical stability was assessed using mixed-effects models and was used to identify thresholds for physiologically relevant changes.

RESULTS

Repeated LCI measurements of acceptable quality (N = 858) were available in 100 patients with CF; for 74 patients, 399 visits at clinical stability were available. The variability of repeated LCI measurements over time expressed as the coefficient of variation (CV%) was 7.4%. The upper limit of normal (ULN) for relative changes in LCI between visits was 19%.

CONCLUSION

We report the variability of LCI in children and adolescents with CF during routine clinical surveillance. According to our data, a change in LCI beyond 19% may be considered physiologically relevant. These findings will help guide clinical decisions according to LCI changes.

Estimating the minimum sample size for interventional and observational studies using the lung clearance index as an endpoint✰

BACKGROUND

With the increasing availability of highly effective modulators for people living with cystic fibrosis (CF), there is a need to re-design research studies to reflect the changing epidemiology of the CF population. The lung clearance index (LCI), a sensitive physiological measure of lung function, may be ideally suited as an endpoint in the era of CF modulator therapies. In this study we describe study design considerations for implementing LCI into interventional and observational research.

METHODS

Simulations were used to estimate the required sample size to detect a range of treatment effects for interventional studies (including cross-over trials) and to track lung disease progression in observational studies.

RESULTS

Using published treatment effects to inform the design of prospective studies can lead to inefficient study designs. Large improvements in LCI for a few individuals can skew results and can influence interpretations of treatment effects. Adjusting for baseline LCI can help to improve the efficiency of a study. Compared to the forced expiratory volume in 1 second (FEV₁), analysis using LCI as an endpoint requires as little as one third of the total sample size.

CONCLUSIONS

Planning of prospective studies that include LCI as an endpoint need to consider baseline LCI and disease severity of the study population; whereas interpretation of results needs to consider whether a few individuals skew the overall treatment effect.

Real-world Associations of US Cystic Fibrosis Newborn Screening Programs With Nutritional and Pulmonary Outcomes

IMPORTANCE

Newborn screening (NBS) for cystic fibrosis (CF) has been universal in the US since 2010, but its association with clinical outcomes is unclear.

OBJECTIVE

To describe the real-world effectiveness of NBS programs for CF in the US on outcomes up to age 10 years.

DESIGN, SETTING, AND PARTICIPANTS

This was a retrospective cohort study using CF Foundation Patient Registry data from January 1, 2000, to December 31, 2018. The staggered implementation of NBS programs by state was used to compare longitudinal outcomes among children in the same birth cohort born before vs after the implementation of NBS for CF in their state of birth. Participants included children with an established diagnosis of CF born between January 1, 2000, to December 31, 2018, in any of the 44 states that implemented NBS for CF between 2003 and 2010. Data were analyzed from October 5, 2020, to April 22, 2022.

EXPOSURES

Birth before vs after the implementation of NBS for CF in the state of birth.

MAIN OUTCOMES AND MEASURES

Longitudinal trajectory of height and weight percentiles from diagnosis, lung function (forced expiratory volume in 1 second, [FEV1] percent predicted) from age 6 years, and age at initial and chronic infection with Pseudomonas aeruginosa using linear mixed-effects and time-to-event models adjusting for birth cohort and potential confounders.

RESULTS

A total of 9571 participants (4713 female participants [49.2%]) were eligible for inclusion, with 4510 (47.1%) in the pre-NBS cohort. NBS was associated with higher weight and height percentiles in the first year of life (weight, 6.0; 95% CI, 3.1-8.4; height, 6.6; 95% CI, 3.8-9.3), but these differences decreased with age. There was no association between NBS and FEV1 at age 6 years, but the percent-predicted FEV1 did increase more rapidly with age in the post-NBS cohort. NBS was associated with older age at chronic P aeruginosa infection (hazard ratio, 0.69; 95% CI, 0.54-0.89) but not initial P aeruginosa infection (hazard ratio, 0.88; 95% CI, 0.77-1.01).

CONCLUSIONS AND RELEVANCE

NBS for CF in the US was associated with improved nutritional status up to age 10 years, a more rapid increase in lung function, and delayed chronic P aeruginosa infection. In the future, as highly effective modulator therapies become available for infants with CF, NBS will allow for presymptomatic initiation of these disease-modifying therapies before irreversible organ damage.

Defining and identifying early-onset lung disease in cystic fibrosis with cumulative clinical characteristics

BACKGROUND

Because of the heterogeneity in cystic fibrosis (CF) lung disease among young children, a clinical method to identify early-onset lung disease is needed.

OBJECTIVE

To develop a CF early-onset lung disease (CFELD) scoring system by utilizing prospectively collected longitudinal data on manifestations in the first 3 years of life.

DESIGN

We studied 145 infants born during 2012-2017, diagnosed through newborn screening by age 3 months, and followed to 36 months of age. Cough severity, pulmonary exacerbations (PEx), respiratory cultures, and hospitalizations were collected at each CF center visit (every 1-2 months in infancy and quarterly thereafter). These data were used to construct the CFELD system and to classify lung disease into five categories: asymptomatic, minimal, mild, moderate, and severe.

RESULTS

The most frequent manifestation of CF early lung disease was MD-reported PEx episodes, PEx hospitalizations, and positive Pseudomonas aeruginosa cultures. Parent-reported cough severity was correlated with the number of respiratory hospitalizations (r = 0.48, p < 0.0001). The distribution of CFELD categories was 10% asymptomatic, 17% minimal, 29% mild, 33% moderate, and 12% severe. The moderate and severe categories occurred threefold higher in pancreatic insufficient (PI, 49%) versus sufficient subjects (16%), p < 0.0001. In addition to PI, gastrointestinal and nutrition-related hospitalizations, plasma cytokines interleukin (IL)-6 and IL-10, duration of CFTR modulator therapy, and type of health insurance were significant predictors of CFELD scores.

CONCLUSION

The CFELD scoring system is novel, allows systematic evaluation of lung disease prognosis early, and may aid in therapeutic decision-making particularly in the initiation of CFTR modulator therapy.

The effect of inhaled hypertonic saline on lung structure in children aged 3-6 years with cystic fibrosis (SHIP-CT): a multicentre, randomised, double-blind, controlled trial

BACKGROUND

In the Saline Hypertonic in Preschoolers (SHIP) study, inhaled 7% hypertonic saline improved the lung clearance index in children aged 3-6 years with cystic fibrosis, but it remained unclear whether improvement is also seen in structural lung disease. We aimed to assess the effect of inhaled hypertonic saline on chest CT imaging in children aged 3-6 years with cystic fibrosis.

METHODS

Children with cystic fibrosis were enrolled in this multicentre, randomised, double-blind, controlled study at 23 cystic fibrosis centres in Spain, Denmark, the Netherlands, Italy, France, Belgium, the USA, Canada, and Australia. Eligible participants were children aged 3-6 years who were able to cooperate with chest CT imaging and comply with daily nebuliser treatment. Participants were randomly assigned 1:1 to receive inhaled 2 puffs of 100 μg salbutamol followed by 4mL of either 7% hypertonic saline or 0·9% isotonic saline twice per day for 48 weeks. Randomisation was stratified by age in North America and Australia, and by age and country in Europe. Chest CTs were obtained at baseline and 48 weeks and scored using the Perth-Rotterdam Annotated Grid Morphometric Analysis for Cystic Fibrosis (PRAGMA-CF) method. The primary outcome was the difference between groups in the percentage of total lung volume occupied by abnormal airways (PRAGMA-CF %Disease) measured by chest CT at 48 weeks. Analysis was by intention-to-treat. This study is registered with Clinicaltrials.gov, NCT02950883.

FINDINGS

Between May 24, 2016, and Dec 18, 2019, 134 children were assessed for inclusion. 18 patients were excluded (nine had incomplete or unsuccessful chest CT at enrolment visit, two could not comply with CT training, two had acute respiratory infection, two withdrew consent, two for reasons unknown, and one was already on hypertonic saline). 116 participants were enrolled and randomly assigned to hypertonic saline (n=56) or isotonic saline (n=60). 12 patients dropped out of the study (seven in the hypertonic saline group and five in the isotonic saline group). Mean PRAGMA-CF %Disease at 48 weeks was 0·88% (95% CI 0·60-1·16) in the hypertonic saline group and 1·55% (1·25-1·84) in the isotonic saline group (mean difference 0·67%, 95% CI 0·26-1·08; p=0·0092) based on a linear regression model adjusted for baseline %Disease values and baseline age. Most adverse events in both groups were rated as mild, and the most common adverse event in both groups was cough.

INTERPRETATION

Inhaled hypertonic saline for 48 weeks had a positive effect on structural lung changes in children aged 3-6 years with cystic fibrosis relative to isotonic saline. This is the first demonstration of an intervention that alters structural lung disease in children aged 3-6 years with cystic fibrosis.

FUNDING

Cystic Fibrosis Foundation.

Predictive value of impulse oscillometry and multiple breath washout parameters in pediatric patients with cystic fibrosis pulmonary exacerbation

BACKGROUND

Pulmonary exacerbations (PE) tend to complicate the course of cystic fibrosis (CF) and worsen the disease prognosis. One of the diagnostic criteria for an exacerbation is the forced expiratory volume in the first second (FEV₁ ) decline. Not all children, however, are able to perform spirometry. Therefore, the aim of this study was to evaluate alternative lung function tests in the diagnosis of PE.

METHODS

We assessed retrospectively the results of impulse oscillometry (IOS) and lung clearance index in multiple breath washout (MBW) during 259 visits in 47 CF paediatric patients. The differences in the results were compared between patients diagnosed with PE (ΔPE) and those in stable condition (ΔS).

RESULTS

Among the whole group of patients, we found significant differences between the changes during exacerbation (ΔPEs) and stable condition (ΔSs) values for lung clearance index (LCI), S_acin , R5Hz, R5-20Hz, X10Hz, AX, and Fres. The predictive values of Fres and X10Hz in IOS (AUC^ROC 0.71 both parameters) were higher than those of LCI (AUC^ROC 0.67). There was no difference in the predictive values (AUC^ROC ) of Δ LCI and IOS parameters in the subgroups of patients stratified based on FEV₁ z-score cut-off value of -1.64. In both groups of patients, predictive values of LCI were slightly lower than of IOS parameters (AUC 0.66 for LCI vs. 0.69 for both ΔX10Hz z-score and Δ Fres z-score in patients with FEV₁ z-score ≥-1.64 and AUC 0.67 for LCI vs 0.69 for both ΔX10Hz zscore and Δ Fres zscore in patients with FEV₁ <1.64.

CONCLUSIONS

Both IOS and MBW measurements are useful in the assessment of pediatric CF patients with PE. LCI has a similar predictive value to IOS in children with CF independently of their FEV₁ value.

Does newborn screening improve early lung function in cystic fibrosis?

Despite evidence showing an improvement in nutritional outcomes following diagnosis by newborn screening (NBS) for cystic fibrosis (CF), the impact on pulmonary outcomes has been less clear. In this review the approaches to measurement of early lung function and knowledge gained from NBS CF cohorts will be described. Studies which have compared outcomes in those diagnosed by NBS to those diagnosed following symptomatic presentation will be presented. Compiling the evidence base used to evaluate the impact of NBS on pulmonary outcomes has been complicated by improvements in clinical management, infection control practices, as well as public health interventions (such as tobacco smoking bans in public places) that have evolved substantially over recent decades. Forced expiratory volumes have been used as the main outcome but it is important not to draw conclusions for 'early lung function' from tests such as spirometry alone, which lack sensitivity in early lung disease. There is, at present, insufficient evidence to draw firm conclusions about the effect of NBS on early lung function. In an era of highly effective treatments targeting the underlying molecular defect responsible for CF, future opportunities for early initiation of treatment may mean that the impact of NBS on early lung function may yet to be realised.

Chest X-rays are less sensitive than multiple breath washout examinations when it comes to detecting early cystic fibrosis lung disease

AIM

Annual chest X-ray is recommended as routine surveillance to track cystic fibrosis (CF) lung disease. The aim of this study was to investigate the clinical utility of chest X-rays to track CF lung disease.

METHODS

Children at Gothenburg's CF centre who underwent chest X-rays, multiple breath washouts and chest computed tomography examinations between 1996 and 2016 were included in the study. Chest X-rays were interpreted with Northern Score (NS). We compared NS to lung clearance index (LCI) and structural lung damage measured by computed tomography using a logistic regression model.

RESULTS

A total of 75 children were included over a median period of 13 years (range: 3.0-18.0 years). The proportion of children with abnormal NS was significantly lower than the proportion of abnormal LCI up to the age of 4 years (p < 0.05). A normal NS and a normal LCI at age 6 years were associated with a median (10-90th percentile) total airway disease of 1.8% (0.4-4.7%) and bronchiectasis of 0.2% (0.0-1.5%).

CONCLUSION

Chest X-rays were less sensitive than multiple breath washout examinations to detect early CF lung disease. The combined results from both methods can be used as an indicator to perform chest computed tomography less frequently.

Effects of Elexacaftor/Tezacaftor/Ivacaftor Therapy on Lung Clearance Index and Magnetic Resonance Imaging in Patients with Cystic Fibrosis and One or Two F508del Alleles

RATIONALE

We recently demonstrated that triple combination CFTR modulator therapy with elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) improves CFTR function in airway and intestinal epithelia to 40 to 50% of normal in patients with cystic fibrosis (CF) with one or two F508del alleles. In previous studies, this improvement of CFTR function was shown to improve clinical outcomes, however, effects on the lung clearance index (LCI) determined by multiple breath washout and abnormalities in lung morphology and perfusion detected by magnetic resonance imaging (MRI) have not been studied.

OBJECTIVES

To examine the effect of ELX/TEZ/IVA on LCI and lung MRI scores in patients with CF and one or two F508del alleles aged 12 years and older.

METHODS

This prospective, observational, multicenter, post-approval study assessed LCI and lung MRI scores before and 8-16 weeks after initiation of ELX/TEZ/IVA.

MEASUREMENTS AND MAIN RESULTS

A total of 91 patients with CF including 45 heterozygous for F508del and a minimal function mutation (MF) and 46 homozygous for F508del were enrolled in this study. Treatment with ELX/TEZ/IVA improved LCI in F508del/MF (-2.4;IQR, -3.7 - -1.1;P<0.001) and F508del homozygous (-1.4;IQR, -2.4 - -0.4;P<0.001) patients. Further, ELX/TEZ/IVA improved the MRI global score in F508del/MF (-6.0;IQR, -11.0 - -1.3;P<0.001) and F508del homozygous (-6.5;IQR, -11.0 - -1.3;P<0.001) patients.

CONCLUSIONS

Our data demonstrate that improvement of CFTR function by ELX/TEZ/IVA improves lung ventilation and abnormalities in lung morphology including airway mucus plugging and wall thickening in adolescent and adult patients with CF and one or two F508del alleles in a real-world, post-approval setting.

ERS International Congress 2021: highlights from the Paediatric Assembly

In this review, Early Career Members of the European Respiratory Society (ERS) and the Chairs of the ERS Assembly 7: Paediatrics present the highlights in paediatric respiratory medicine from the ERS International Congress 2021. The eight scientific Groups of this Assembly cover respiratory physiology and sleep, asthma and allergy, cystic fibrosis (CF), respiratory infection and immunology, neonatology and intensive care, respiratory epidemiology, bronchology, and lung and airway development. We here describe new developments in lung function testing and sleep-disordered breathing diagnosis, early life exposures affecting pulmonary function in children and effect of COVID-19 on sleep and lung function. In paediatric asthma, we present the important role of the exposome in asthma development, and how biologics can provide better outcomes. We discuss new methods to assess distal airways in children with CF, as some details remain blind when using the lung clearance index. Moreover, we summarise the new ERS guidelines for bronchiectasis management in children and adolescents. We present interventions to reduce morbidity and monitor pulmonary function in newborns at risk of bronchopulmonary dysplasia and long-term chronic respiratory morbidity of this disease. In respiratory epidemiology, we characterise primary ciliary dyskinesia, identify early life determinants of respiratory health and describe the effect of COVID-19 preventive measures on respiratory symptoms. Also, we describe the epidemiology of interstitial lung diseases, possible consequences of tracheomalacia and a classification of diffuse alveolar haemorrhage in children. Finally, we highlight that the characterisation of genes and pathways involved in the development of a disease is essential to identify new biomarkers and therapeutic targets.

Multiple breath washout: measuring early manifestations of lung pathology

The multiple breath washout (MBW) test measures the efficiency of gas mixing in the lungs and has gained significant interest over the past 20 years. MBW outcomes detect early lung function impairment and peripheral airway pathology, through its main outcome measure lung clearance index (LCI). LCI measures the number of lung turnovers required to washout an inert tracer gas. MBW is performed during normal (tidal) breathing, making it particularly suitable for young children or those who have trouble performing forced manoeuvres. Additionally, research in chronic respiratory disease populations has shown that MBW can detect acute clinically relevant changes before conventional lung function tests, such as spirometry, thus enabling early intervention. The development of technical standards for MBW and commercial devices have allowed MBW to be implemented in clinical research and potentially routine clinical practice. Although studies have summarised clinimetric properties of MBW indices, additional research is required to establish the clinical utility of MBW and, if possible, shorten testing time. Sensitive, feasible measures of early lung function decline will play an important role in early intervention for people living with respiratory diseases.

Educational aim

To describe the multiple breath washout test, its applications to lung pathology and respiratory disease, as well as directions for future research.

Burden of cystic fibrosis in children <12 years of age prior to the introduction of CFTR modulator therapies

Background

Cystic fibrosis (CF) is a genetic, multisystemic, progressive and life-shortening disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. Different genotypes have been linked to variations in disease progression among people with CF. The burden of illness (BOI) in children with CF is incompletely characterised, particularly as it relates to CFTR genotypes prior to the availability of the first CFTR modulators. This retrospective, cross-sectional, descriptive study evaluated the BOI in US children with CF <12 years of age prior to the first approval of CFTR modulators.

Methods

Data from the US Cystic Fibrosis Foundation Patient Registry from 2011 were used to summarise key patient and disease characteristics using descriptive statistics, overall and grouped by age (0 to <2 years, 2 to <6 years and 6 to <12 years) and genotype (F508del/F508del, F508del/minimal function (MF), MF/MF, gating mutation on ≥1 allele, residual function mutation on ≥1 allele and R117H on ≥1 allele) group.

Results

The analysis included 9185 children. Among 6-year-olds to <12-year-olds, mean (SD) per cent predicted FEV₁ in 1 s was 92.6% (17.5%). Among all children <12 years of age, the mean (SD) all-cause hospitalisation and pulmonary exacerbation rates in 2011 were 0.4 (1.0) and 0.3 (0.8), respectively. Most (93.6%) had ≥1 positive lung microbiology culture. CF-related medication and nutritional supplementation use was common across all ages and genotypes. More than half (54.7%) had ≥1 CF-related complication. Evidence of disease burden was observed across the age and genotype groups studied.

Conclusions

Prior to the approval of the first CFTR modulator therapies in children <12 years of age, CF was associated with substantial BOI from an early age—including respiratory infections, hospitalisations/pulmonary exacerbations, need for supplemental nutrition and pharmacological treatments—irrespective of genotype.

Outcomes of Cystic Fibrosis Screening-Positive Infants With Inconclusive Diagnosis at School Age

BACKGROUND AND OBJECTIVES

Cystic fibrosis (CF) screen-positive infants with an inconclusive diagnosis (CFSPID) are infants in whom sweat testing and genetic analysis does not resolve a CF diagnosis. Lack of knowledge about the health outcome of these children who require clinical follow-up challenges effective consultation. Early predictive biomarkers to delineate the CF risk would allow a more targeted approach to these children.

METHODS

Prospective, longitudinal, multicenter, Canada-wide cohort study of CF positive-screened newborns with 1 to 2 cystic fibrosis transmembrane conductance regulator gene variants, of which at least 1 is not known to be CF-causing and/or a sweat chloride between 30 and 59 mmol/L. These were monitored for conversion to a CF diagnosis, pulmonary, and nutritional outcomes.

RESULTS

The mean observation period was 7.7 (95% confidence interval 7.1 to 8.4) years. A CF diagnosis was established for 24 of the 115 children with CFSPID (21%) either because of reinterpretation of the cystic fibrosis transmembrane conductance regulator genotype or because of increase in sweat chloride concentration ≥60 mmol/L. An initial sweat chloride of ≥40 mmol/l predicted conversion to CF on the basis of sweat testing. The 91 remaining children with CFSPID were pancreatic sufficient and showed normal growth until school age. Pulmonary function as well as lung clearance index in a subgroup of children with CFSPID were similar to that of healthy controls.

CONCLUSIONS

Children with CFSPID have good nutritional and pulmonary outcomes at school age, but rates of reclassifying the diagnosis are high. The initial sweat chloride test can be used as a biomarker to predict the risk for CF in CFSPID.

Correction of sensor crosstalk error in Exhalyzer D multiple-breath washout device significantly impacts outcomes in children with cystic fibrosis

Nitrogen multiple-breath washout is an established technique to assess functional residual capacity and ventilation inhomogeneity in the lung. Accurate measurement of gas concentrations is essential for the appropriate calculation of clinical outcomes. We investigated the accuracy of oxygen and carbon dioxide gas sensor measurements used for the indirect calculation of nitrogen concentration in a commercial multiple-breath washout device (Exhalyzer D, Eco Medics AG, Duernten, Switzerland) and its impact on functional residual capacity and lung clearance index. High-precision calibration gas mixtures and mass spectrometry were used to evaluate sensor output. We assessed the impact of corrected signal processing on multiple-breath washout outcomes in a data set of healthy children and children with cystic fibrosis using custom analysis software. We found inadequate correction for the cross sensitivity of the oxygen and carbon dioxide sensors in the Exhalyzer D device. This results in an overestimation of expired nitrogen concentration and consequently, multiple-breath washout outcomes. Breath-by-breath correction of this error reduced the mean (SD) cumulative expired volume by 19.6% (5.0%), functional residual capacity by 8.9% (2.2%), and lung clearance index by 11.9% (4.0%). It also substantially reduced the level of the tissue nitrogen signal at the end of measurements. Inadequate correction for cross sensitivity in the oxygen and carbon dioxide gas sensors of the Exhalyzer D device leads to an overestimation of functional residual capacity and lung clearance index. Correction of this error is possible and could be applied by reanalyzing the measurements in an updated software version.NEW & NOTEWORTHY We investigated the sensor accuracy of a prominent nitrogen multiple-breath washout (N2MBW) device (Eco Medics AG, Duernten, Switzerland) as a possible cause of lack of comparability between outcomes of different MBW devices and methods. We identified an error in the nitrogen concentration calculation of this device, which results in a 10%-15% overestimation of primary outcomes, functional residual capacity, and lung clearance index. It also leads to a significant overestimation of nitrogen back-diffusion into the lungs.

Pulmonary Dysfunction after Treatment for Childhood Cancer. Comparing Multiple-Breath Washout with Spirometry

Rationale: Childhood cancer survivors are at risk of long-term pulmonary dysfunction, but we lack sensitive outcome measures to detect early pulmonary damage.Objectives: To assess the ability of nitrogen multiple-breath washout (N₂MBW) for detecting pulmonary dysfunction compared with spirometry in long-term survivors of childhood cancer.Methods: We analyzed cross-sectional data from long-term (≥5-yr) survivors of childhood cancer, aged ≤16 years at cancer diagnosis, ≥16 years at study (assessment period 2015-2019). We categorized survivors by risk: high risk for those having had pulmotoxic chemotherapy, chest radiation, thoracic surgery, and/or hematopoietic stem cell transplantation, and standard risk for other cancer therapies. Primary outcomes were the global lung clearance index (LCI) and acinar ventilation inhomogeneity index (S_ACIN) from N₂MBW, and forced expiratory volume in 1 second (FEV₁) and functional vital capacity (FVC) from spirometry. We calculated z-scores for N₂MBW and spirometry parameters and compared pulmonary dysfunction between risk groups. Pulmonary dysfunction was defined as z-score +1.64 for N₂MBW and -1.64 for spirometry.Results: We studied 46 survivors, median age at diagnosis 10 years (interquartile range, 4-14), median age at study 30 years (interquartile range, 25-40). Thirty-seven percent were at high risk and 63% at standard risk for pulmonary dysfunction. LCI and S_ACIN were higher in the high-risk group compared with the standard-risk group (mean LCI z-scores 2.09, standard deviation [SD] 2.39 vs. 0.95, SD 2.81; mean S_ACIN z-scores 2.45, SD 3.29 vs. 0.65, SD 2.79). FEV₁ and FVC were lower in the high-risk compared with the standard-risk group (mean FEV₁ z-scores -0.94, SD 1.39 vs. -0.10, SD 1.07; mean FVC z-scores -1.14, SD 1.23 vs. 0.15, SD 1.61). Overall, LCI, S_ACIN, FEV₁, and FVC were abnormal in 60%, 53%, 33%, and 33% of high-risk patients compared with 23%, 21%, 0%, and 4% of standard-risk patients.Conclusions: N₂MBW identified more cases of pulmonary dysfunction in long-term survivors of childhood cancer than spirometry, even in patients who had cancer therapy not specifically known as being pulmotoxic. N₂MBW could be a complementary screening tool for early pulmonary damage after treatment for childhood cancer.Clinical trial registered with www.clinicaltrials.gov (NCT02730767).

Longitudinal assessment of lung clearance index to monitor disease progression in children and adults with cystic fibrosis

Background

Lung clearance index (LCI) is a valuable research tool in cystic fibrosis (CF) but clinical application has been limited by technical challenges and uncertainty about how to interpret longitudinal change. In order to help inform clinical practice, this study aimed to assess feasibility, repeatability and longitudinal LCI change in children and adults with CF with predominantly mild baseline disease.

Methods

Prospective, 3-year, multicentre, observational study of repeated LCI measurement at time of clinical review in patients with CF >5 years, delivered using a rapid wash-in system.

Results

112 patients completed at least one LCI assessment and 98 (90%) were still under follow-up at study end. The median (IQR) age was 14.7 (8.6–22.2) years and the mean (SD) FEV₁ z-score was −1.2 (1.3). Of 81 subjects with normal FEV₁ (>−2 z-scores), 63% had raised LCI (indicating worse lung function). For repeat stable measurements within 6 months, the mean (limits of agreement) change in LCI was 0.9% (−18.8% to 20.7%). A latent class growth model analysis identified four discrete clusters with high accuracy, differentiated by baseline LCI and FEV₁. Baseline LCI was the strongest factor associated with longitudinal change. The median total test time was under 19 min.

Conclusions

Most patients with CF with well-preserved lung function show stable LCI over time. Cluster behaviours can be identified and baseline LCI is a risk factor for future progression. These results support the use of LCI in clinical practice in identifying patients at risk of lung function decline.

Magnetic Resonance Imaging Detects Progression of Lung Disease and Impact of Newborn Screening in Preschool Children with Cystic Fibrosis

RATIONALE

Previous cross-sectional studies demonstrated that chest magnetic resonance imaging (MRI) is sensitive to detect early lung disease in infants and preschool children with cystic fibrosis (CF) without radiation exposure. However, the ability of MRI to detect progression of lung disease and the impact of early diagnosis in preschool children with CF remains unknown.

OBJECTIVES

To investigate the potential of MRI to detect progression of early lung disease and impact of early diagnosis by CF newborn screening (NBS) in preschool children with CF.

METHODS

Annual MRI was performed from diagnosis over four years in a cohort of 96 preschool children with CF (age 0-4 yr) that were concurrently diagnosed based on NBS (n=28) or clinical symptoms (n=68). MRI scans were evaluated using a dedicated morphofunctional score and the relationship between longitudinal MRI scores and respiratory symptoms, pulmonary exacerbations, upper airway microbiology and mode of diagnosis were determined.

MEASUREMENTS AND MAIN RESULTS

The MRI global score increased in the total cohort of children with CF during preschool years (P<0.001) which was associated with cough, pulmonary exacerbations (P<0.0001), and detection of Staphylococcus aureus and Haemophilus influenzae (P<0.05). MRI-defined abnormalities in lung morphology, especially airway wall thickening/bronchiectasis, were lower in NBS compared to clinically diagnosed children with CF throughout the observation period (P<0.01).

CONCLUSIONS

MRI detected progression of early lung disease and benefits of early diagnosis by NBS in preschool children with CF. These findings support MRI as sensitive outcome measure for diagnostic monitoring and early intervention trials in preschool children with CF.

Determinants of lung disease progression measured by lung clearance index in children with cystic fibrosis

The lung clearance index (LCI) measured by the multiple breath washout (MBW) test is sensitive to early lung disease in children with cystic fibrosis. While LCI worsens during the preschool years in cystic fibrosis, there is limited evidence to clarify whether this continues during the early school age years, and whether the trajectory of disease progression as measured by LCI is modifiable.A cohort of children (healthy and cystic fibrosis) previously studied for 12 months as preschoolers were followed during school age (5-10 years). LCI was measured every 3 months for a period of 24 months using the Exhalyzer D MBW nitrogen washout device. Linear mixed effects regression was used to model changes in LCI over time.A total of 582 MBW measurements in 48 healthy subjects and 845 measurements in 64 cystic fibrosis subjects were available. The majority of children with cystic fibrosis had elevated LCI at the first preschool and first school age visits (57.8% (37 out of 64)), whereas all but six had normal forced expiratory volume in 1 s (FEV₁) values at the first school age visit. During school age years, the course of disease was stable (-0.02 units·year^-1 (95% CI -0.14-0.10). LCI measured during preschool years, as well as the rate of LCI change during this time period, were important determinants of LCI and FEV_1, at school age.Preschool LCI was a major determinant of school age LCI; these findings further support that the preschool years are critical for early intervention strategies.

Longitudinal course of clinical lung clearance index in children with cystic fibrosis

BACKGROUND

Although the lung clearance index (LCI) is a sensitive marker of small airway disease in individuals with cystic fibrosis (CF), less is known about longitudinal changes in LCI during routine clinical surveillance. Here, our objectives were to describe the longitudinal course of LCI in children with CF during routine clinical surveillance and assess influencing factors.

METHODS

Children with CF aged 3-18 years performed LCI measurements every 3 months as part of routine clinical care between 2011 and 2018. We recorded clinical data at every visit. We used a multilevel mixed effect model to determine changes in LCI over time and identify clinical factors that influence LCI course.

RESULTS

We collected LCI measurements from 1204 visits (3603 trials) in 78 participants, of which 907 visits had acceptable LCI data. The average unadjusted increase in LCI for the entire population was 0.29 (95% CI 0.20-0.38) LCI units·year^-1. The increase in LCI was more pronounced in adolescence (0.41 (95% CI 0.27-0.54) LCI units·year^-1). Colonisation with either Pseudomonas aeruginosa or Aspergillus fumigatus, pulmonary exacerbations, CF-related diabetes and bronchopulmonary aspergillosis were associated with a higher increase in LCI over time. Adjusting for clinical risk factors reduced the increase in LCI over time to 0.24 (95% CI 0.16-0.33) LCI units·year^-1.

CONCLUSIONS

LCI measured during routine clinical surveillance is associated with underlying disease progression in children with CF. An increased change in LCI over time should prompt further diagnostic intervention.