Elevated lung clearance index in infants with cystic fibrosis shortly after birth

Lung structural and functional impairments in young children with cystic fibrosis diagnosed following newborn screening - A nationwide observational study

BACKGROUND

Non-invasive and sensitive clinical endpoints are needed to monitor onset and progression of early lung disease in children with cystic fibrosis (CF). We compared lung clearance index (LCI), FEV1, functional and structural lung magnetic resonance imaging (MRI) outcomes in Swiss children with CF diagnosed following newborn screening.

METHODS

Lung function (LCI, FEV1) and unsedated functional and structural lung MRI was performed in 79 clinically stable children with CF (3 - 8 years) and 75 age-matched healthy controls. Clinical information was collected throughout childhood.

RESULTS

LCI, ventilation and perfusion defects, and structural MRI scores were significantly higher in children with CF compared with controls, but FEV1 was not different between groups. Lung MRI outcomes correlated significantly with LCI (morphology score (r = 0.56, p < 0.001); ventilation defects (r = 0.43, p = 0.001); perfusion defects (r = 0.64, p < 0.001), but not with FEV1. Lung MRI outcomes were more sensitive to detect impairments in children with CF (abnormal ventilation and perfusion outcomes in 47 %, morphology score in 30 %) compared with lung function (abnormal LCI in 21 % and FEV1 in 4.8 %). Pulmonary exacerbations, respiratory hospitalizations, and increase in patient-reported cough was associated with higher LCI and higher structural and functional MRI outcomes.

CONCLUSIONS

The LCI and lung MRI outcomes non-invasively detect even mild early lung disease in young children with CF diagnosed following newborn screening. Pulmonary exacerbations and early respiratory symptoms were risk factors for structural and functional impairment in childhood.

In utero smoking exposure induces changes to lung clearance index and modifies risk of wheeze in infants

BACKGROUND

Fetal exposure to tobacco smoking throughout pregnancy is associated with wheezing in infancy. We investigated the influence of in utero smoking exposure on lung ventilation homogeneity and the relationship between lung ventilation inhomogeneity at 7 weeks of age and wheezing in the first year of life.

METHODS

Maternal smoking was defined as self-reported smoking of tobacco or validated by exhaled (e)CO > 6 ppm. Lung function data from healthy infants (age 5-9 weeks) born to asthmatic mothers and parent-reported respiratory questionnaire data aged 12 months were collected in the Breathing for Life Trial (BLT) birth cohort. Tidal breathing analysis and SF6-based Multiple Breath Washout testing were performed in quiet sleep. Descriptive statistics and regression analysis were used to assess associations.

RESULTS

Data were collected on 423 participants. Infants born to women who self-reported smoking during pregnancy (n = 42) had higher lung clearance index (LCI) than those born to nonsmoking mothers (7.90 vs. 7.64; p = .030). Adjusted regression analyzes revealed interactions between self-reported smoking and LCI (RR: 1.98, 95% CI: 1.07-3.63, 0.028, for each unit increase in LCI) and between eCO > 6 ppm and LCI (RR: 2.25, 95% CI: 1.13-4.50, 0.022) for the risk of wheeze in the first year of life.

CONCLUSION

In utero tobacco smoke exposure induces lung ventilation inhomogeneities. Furthermore, an interaction between smoke exposure and lung ventilation inhomogeneities increases the risk of having a wheeze in the first year of life.

Standards for the care of people with cystic fibrosis; establishing and maintaining health

This is the second in a series of four papers updating the European Cystic Fibrosis Society (ECFS) standards for the care of people with CF. This paper focuses on establishing and maintaining health. The guidance is produced using an evidence-based framework and with wide stakeholder engagement, including people from the CF community. Authors provided a narrative description of their topic and statements, which were more directive. These statements were reviewed by a Delphi exercise, achieving good levels of agreement from a wide group for all statements. This guidance reinforces the importance of a multi-disciplinary CF team, but also describes developing models of care including virtual consultations. The framework for health is reinforced, including the need for a physically active lifestyle and the strict avoidance of all recreational inhalations, including e-cigarettes. Progress with cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy is reviewed, including emerging adverse events and advice for dose reduction and interruption. This paper contains guidance that is pertinent to all people with CF regardless of age and eligibility for and access to modulator therapy.

Nationwide lung function monitoring from infancy in newborn-screened children with cystic fibrosis

Background

Cystic fibrosis (CF) lung disease starts in infancy and can be assessed for structural lung abnormalities using computed tomography or magnetic resonance scans, or for lung function impairment using multiple breath washout (MBW). However, in infancy these two methods are not well correlated. Trajectories of CF lung disease assessed by MBW in infants and toddlers remain poorly described, which is why we aimed to 1) describe the trajectory of lung function, 2) explore risk factors for progression and 3) explore the real-life effect of lumacaftor/ivacaftor.

Methods

This was a nationwide observational cohort study (2018-2021) using data collected as part of the routine clinical surveillance programme (including MBW and monthly endo-laryngeal suction sampling for bacterial pathogens) in children born after implementation of newborn screening for CF (May 2016). Lumacaftor/ivacaftor commenced from age 2 years in children homozygous for F508del. Ventilation distribution efficiency (VDE), recently described to have advantages over lung clearance index (LCI), was reported as the primary MBW outcome after z-score calculations based on published reference data. Mixed effect linear regression models were the main statistical analyses performed in this study.

Results

59 children, aged 2-45 months, contributed with 211 MBW occasions (median (interquartile range (IQR)) 3 (2-5) MBW occasions per child) with a median (IQR) follow-up time of 10.8 (5.2-22.3) months. An overall mean annual deterioration rate of -0.50 (95% CI -0.78- -0.22) z-VDE was observed, starting from an estimated mean z-VDE of -1.68 (95% CI -2.15- -1.22) at age 0.0 years (intercept). Pseudomonas aeruginosa "ever" (n=14, MBWs 50) had a significantly worse z-VDE trajectory versus P. aeruginosa "never" (mean difference 0.53 (95% CI 0.16-0.89) per year; p=0.0047) and lumacaftor/ivacaftor treatment (n=22, MBWs 46) significantly improved the trajectory of z-VDE (mean difference 1.72 (95% CI 0.79-2.66) per year; p=0.0004), leading to a stable mean z-VDE trajectory after start of treatment.

Conclusions

Infants and toddlers with CF demonstrated progressive deterioration in z-VDE over the first years of life. P. aeruginosa isolation "ever" was associated with an accelerated deterioration in lung function, while lumacaftor/ivacaftor therapy significantly improved and stabilised the trajectory.

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.

An Update on CFTR Modulators as New Therapies for Cystic Fibrosis

Over the past decade there have been significant developments in the field of Cystic Fibrosis Transmembrane Regulator modulator drugs. Following treatment in patients with cystic fibrosis with common gating mutations using the potentiator drug ivacaftor, successive development of corrector drugs used in combination has led to highly effective modulator therapy being available to more than 85% of the cystic fibrosis population over 12 years of age in the form of elexacaftor/tezacaftor/ivacaftor. In this article, we review the evidence from clinical trials and mounting real-world observational and registry data that demonstrates the impact highly effective modulators have on both pulmonary and extra-pulmonary manifestations of cystic fibrosis. As clinical trials progress to younger patient groups, we discuss the challenges to demonstrating drug efficacy in early life, and also consider practicalities of drug development in an ever-shrinking modulator-naïve population. Drug-drug interactions are an important consideration in people with cystic fibrosis, where polypharmacy is commonplace, but also as the modulated population look to remain healthier for longer, we identify trials that aim to address treatment burden too. Inequity of care, through drug cost or ineligibility for modulators by genotype, is widening without apparent strategies to address this; however, we present evidence of hopeful early-stage drug development for non-modulatable genes and summarise the current state of gene-therapy development.

Contemporary N2 and SF6 multiple breath washout in infants and toddlers with cystic fibrosis

INTRODUCTION

Multiple breath washout (MBW) is used for early detection of cystic fibrosis (CF) lung disease, with SF₆ MBW commonly viewed as the reference method. The use of N₂ MBW in infants and toddlers has been questioned for technical and physiological reasons, but a new correction of the N₂  signal has minimized the technical part. The present study aimed to assess the remaining differences and the contributing mechanisms for the differences between SF₆ and N₂ MBW,corrected-such as tidal volume reduction during N₂ washout with pure O₂ .

METHOD

This was a longitudinal multicenter cohort study. SF₆ MBW and N₂ MBW were performed prospectively at three CF centers in the same visits on 154 test occasions across 62 children with CF (mean age: 22.7 months). Offline analysis using identical algorithms to the commercially available program provided outcomes of N_2,original and N_2,corrected for comparison with SF₆ MBW.

RESULTS

Mean functional residual capacity, FRC_N2,corrected was 14.3% lower than FRC_{N2, original} , and 1.0% different from FRC_SF6 . Lung clearance index, LCI_N2,corrected was 25.2% lower than LCI_N2,original , and 7.3% higher than LCI_SF6 . Mean (SD) tidal volume decreased significantly during N₂ MBW_corrected , compared to SF₆ MBW (-13.1 ml [-30.7; 4.6], p < 0.0001, equal to -12.0% [-25.7; 1.73]), but this tidal volume reduction did not correlate to the differences between LCI_N2,corrected and LCI_SF6 . The absolute differences in LCI increased significantly with higher LCI_SF6 (0.63/LCI_SF6 ) and (0.23/LCI_SF6 ), respectively, for N_2,original and N_2,corrected , but the relative differences were stable across disease severity for N_2,corrected , but not for N_2,original .

CONCLUSION

Only minor residual differences between FRC_N2,corrected and FRC_SF6 remained to show that the two methods measure gas volumes very similar in this age range. Small differences in LCI were found. Tidal volume reduction during N₂ MBW did not affect differences. The corrected N₂ MBW can now be used with confidence in young children with CF, although not interchangeably with SF₆ .

Hyperinflation is associated with increased respiratory rate and is a more sensitive measure of cystic fibrosis lung disease during infancy compared to forced expiratory measures

BACKGROUND

The goal of this study was to identify clinical features associated with abnormal infant pulmonary function tests (iPFTs), specifically functional residual capacity (FRC), in infants with cystic fibrosis (CF) diagnosed via newborn screen (NBS). We hypothesized that poor nutritional status in the first 6-12 months would be associated with increased FRC at 12-24 months.

METHODS

This study utilized a combination of retrospectively and prospectively collected data from ongoing research studies and iPFTs performed for clinical indications. Demographic and clinical features were obtained from the electronic medical record. Forced expiratory flows and volumes were obtained using the raised volume rapid thoracoabdominal technique (RVRTC) and FRC was measured via plethysmography.

RESULTS

A total of 45 CF NBS infants had iPFTs performed between 12 and 24 months. Mean forced vital capacity, forced expiratory volume in 0.5 s, and forced expiratory flows were all within normal limits. In contrast, the mean FRC z-score was 2.18 (95% confidence interval [CI] = 1.48, 2.88) and the mean respiratory rate (RR) z-score was 1.42 (95% CI = 0.95, 1.89). There was no significant association between poor nutritional status and abnormal lung function. However, there was a significant association between higher RR and increased FRC, and a RR cutoff of 36 breaths/min resulted in 92% sensitivity to detect hyperinflation with 32% specificity.

CONCLUSION

These results suggest that FRC is a more sensitive measure of early CF lung disease than RVRTC measurements and that RR may be a simple, noninvasive clinical marker to identify CF NBS infants with hyperinflation.

Quantification of Phenotypic Variability of Lung Disease in Children with Cystic Fibrosis

Cystic fibrosis (CF) lung disease has the greatest impact on the morbidity and mortality of patients suffering from this autosomal-recessive multiorgan disorder. Although CF is a monogenic disorder, considerable phenotypic variability of lung disease is observed in patients with CF, even in those carrying the same mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene or CFTR mutations with comparable functional consequences. In most patients with CF, lung disease progresses from childhood to adulthood, but is already present in infants soon after birth. In addition to the CFTR genotype, the variability of early CF lung disease can be influenced by several factors, including modifier genes, age at diagnosis (following newborn screening vs. clinical symptoms) and environmental factors. The early onset of CF lung disease requires sensitive, noninvasive measures to detect and monitor changes in lung structure and function. In this context, we review recent progress with using multiple-breath washout (MBW) and lung magnetic resonance imaging (MRI) to detect and quantify CF lung disease from infancy to adulthood. Further, we discuss emerging data on the impact of variability of lung disease severity in the first years of life on long-term outcomes and the potential use of this information to improve personalized medicine for patients with CF.

Withdrawal of dornase alfa increases ventilation inhomogeneity in children with cystic fibrosis

BACKGROUND

The lung clearance index (LCI) is increasingly used as an outcome in clinical trials of patients with mild cystic fibrosis (CF) lung disease. Yet, understanding the impact of standard CF respiratory therapy on LCI is needed. We assessed to what degree withdrawal of nebulised dornase alfa affected LCI in school-age children with CF not receiving CFTR modulators or hydrator therapy.

METHODS

A single-centre, randomised, controlled, parallel group study to determine effects of one month's withdrawal of nebulised dornase alfa (intervention) in 5-18 years old children with CF. Remaining chronic maintenance therapy stayed unchanged. Outcome measures were assessed at two visits one month apart. Primary outcome was absolute change in LCI. Secondary outcomes were FEV₁, FEF_25-75 and CF Questionnaire-revised (CFQ-R) respiratory symptom score. Possible harmful effects were assessed by comparing the occurrence of pulmonary exacerbations between groups.

RESULTS

Twenty-eight children (median age 10.4 [interquartile range: 7.6; 13.5] years) with CF received standard care (n = 14) or intervention (n = 14). Compared with the control group, LCI increased (worsened) 1.74 (95% confidence interval: 0.62; 2.86) during withdrawal of dornase alfa, while FEV₁ (-6.8% predicted) and FEF_25-75 (-13.1% predicted) decreased significantly. Change in CFQ-R respiratory symptom score and the occurrence of pulmonary exacerbations did not differ significantly between groups.

CONCLUSIONS

One month's withdrawal of dornase alfa caused increasing ventilation inhomogeneity and deteriorating FEV₁ and FEF_25-75 in school-age children with mild CF. Hence, adherence to dornase alfa optimally needs to be addressed when using LCI and spirometric parameters as endpoints, even in short-term clinical trials.

Physical activity and quality of life of children and adolescents with cystic fibrosis: a cross-sectional study

Abstract Introduction: Regular physical activity (PA) is part of outpatient care offered to most people with cystic fibrosis (CF). Objective: To determine the frequency of the self-reported PA and, secondarily evaluate associations between PA with clinical variables and health-related quality of life (HRQoL) in pediatric and adolescent CF subjects. Method: In this cross-sectional study, subjects between 6 and 17 years of age with a confirmed diagnosis of CF were recruited in the outpatient clinic. The subjects answered questions about the practices of PA, HRQoL questionnaire and clinical variables were collected. Subjects were classified into two groups according to weekly PA practice: PA performed ≥ 3 times/week and performed PA ≤ 2 times/week. Results: 66 subjects completed the study, 72.7% (n=48) had PA ≥ 3 times/week and 27.2% (n=18) had PA ≤ 2 times/week. Only twelve children (18,2%) reached the recommendations of the World Health Organization (WHO) to practice moderate to vigorous physical activities daily. The mean age of the subjects evaluated was 12.3 ± 3.2 years, forced expiratory volume in one second 90 ± 24.1% and forced vital capacity 95 ± 20.4%. The group that performed PA ≥ 3 times/week had a better clinical score (p=0.033), a lower number of hospitalizations in the year (p=0.002), a lower number of days hospitalized in the last year (p=0.020) and better score for the physical (p=0.003) and emotion (p=0.048) domains in HRQoL questionnaire. Conclusion: This study concluded that most subjects did not reach the WHO recommendations for the practice of PA. However, individuals who practice PA at least 3 times/week have better HRQoL, clinical score and fewer hospitalizations.

Update on nonpharmacological interventions in parasomnias

Parasomnias are abnormal behaviors that occur during sleep and can be associated, in particular during adulthood, with impaired sleep quality, daytime dysfunction, and occasionally with violent and harmful nocturnal behaviors. In these cases, therapies are often considered. Longterm pharmacological treatments are not always well tolerated and often have limited efficacy. Therefore, behavioral approaches remain an important treatment option for several types of parasomnias. However, the evidence-based approaches are limited. In the current review, we highlight results from various nonpharmacological techniques on different types of parasomnias and provide a glimpse into the future of nonpharmacological treatments in this field.

Pulmonary findings in infants with cystic fibrosis during the first year of life: Results from the Baby Observational and Nutrition Study (BONUS) cohort study

IMPORTANCE

Treatment recommendations for infants with CF standardize care, but most surveillance or treatment guidance of pulmonary manifestations are consensus-based due to sparse evidence.

OBJECTIVE

To report observations about pulmonary correlates of growth and other clinical features in infants with CF.

METHODS

We analyzed data from the prospective Baby Observational and Nutrition Study conducted in 28 centers across the US, including clinical features, medications, guardian diaries of respiratory symptoms, oropharyngeal swab cultures and chest radiographs (CXR) collected over the first year of life.

RESULTS

Cough was reported in 84% of infants in the first year. Up to 30% had clinically important cough but only 6.3% had crackles; 16.5% had wheeze. Wisconsin CXR score was above 5 in 23% (normal = 0; maximum score = 100). Pseudomonas was recovered from at least one respiratory culture in 24% of infants and was associated with crackles/wheezes and use of proton pump inhibitors (PPI) (OR = 5.47; 95%CI = 1.36, 21.92; P = 0.02) or PPI plus histamine-2 (H2) blocker (OR = 8.2; 95%CI = 2.41, 27.93; P = 0.001), but not H2 blocker alone. Hospitalization for respiratory indications occurred in 18% of infants and was associated with crackles/wheeze and abnormal CXR but not low weight, Pseudomonas or use of acid blockade.

CONCLUSIONS

Cough is common in infants with CF, but few present with crackles/wheeze or CXR changes. Pseudomonas is associated with use of PPI or PPI plus H2 blocker, but not with respiratory hospitalization. These observations cannot prove cause and effect but add to our understanding of pulmonary manifestations of CF in infants.

TRIAL REGISTRATION

United States ClinicalTrials.Gov registry NCT01424696 (clinicaltrials.gov).

Nasal Resistome Development in Infants With Cystic Fibrosis in the First Year of Life

Polymicrobial infections of the respiratory tract due to antibiotic resistant bacteria are a great concern in patients with cystic fibrosis (CF). We therefore aimed at establishing a functional metagenomic method to analyze the nasal resistome in infants with CF within the first year of life. We included samples from patients before antibiotic treatment, which allowed obtaining information regarding natural status of the resistome. In total, we analyzed 130 nasal swabs from 26 infants with CF and screened for β-lactams (ampicillin, amoxicillin-clavulanic acid, and cefuroxime) and other classes of antibiotic resistances (tetracycline, chloramphenicol and trimethoprim-sulfamethoxazole). For 69 swabs (53% of total), we found at least one non-susceptible phenotype. Analyses of the inserts recovered from non-susceptible clones by nanopore MinION sequencing revealed a large reservoir of resistance genes including mobile elements within the antibiotic naïve samples. Comparing the data of the resistome with the microbiota composition showed that the bacterial phyla and operational taxonomic units (OTUs) of the microbiota rather than the antibiotic treatment were associated with the majority of non-susceptible phenotypes in the resistome. Future studies will reveal if characterization of the resistome can help in clinical decision-making in patients with CF.

Comparison of lung clearance index determined by washout of N2 and SF6 in infants and preschool children with cystic fibrosis

BACKGROUND

Multiple-breath washout (MBW) has been shown to detect early impairment of lung function in children with cystic fibrosis (CF). Nitrogen (N₂) or sulfur hexafluoride (SF₆) can be used as tracer gas for MBW. Recent data indicated higher lung clearance index (LCI) values measured with N₂-MBW than concurrent SF₆-MBW in older children and adults, however, a comparison in infants and younger children, as well as to other outcome measures of CF lung disease is pending.

METHODS

N₂- and SF₆-MBW were performed consecutively in 31 sedated infants and preschool children with CF (mean age, 2.3 ± 0.8 years) and 20 controls (mean age, 2.3 ± 1.1 years) using the Exhalyzer D system. Children with CF also underwent chest magnetic resonance imaging (MRI).

RESULTS

Mean difference (95% CI) in LCI between N₂- and SF₆-MBW was 1.1 ± 0.4 (0.9 to 1.3) in controls and 2.1 ± 1.9 (1.4 to 2.8) in CF. Agreement between N₂- and SF₆-LCI was poor in children with CF. N₂-LCI and SF₆-LCI correlated with MRI, however N₂-LCI showed a higher concordance with MRI than SF₆-LCI. The absolute difference between N₂- and SF₆-LCI values increased with the severity of CF lung disease as determined by MRI scores.

CONCLUSION

N₂-LCI values were higher than SF₆-LCI values in infants and preschool children with CF and controls. Better concordance of N₂-LCI than SF₆-LCI with chest MRI scores point towards of a higher sensitivity of N₂-LCI to detect early lung disease in children with CF.

Ventilation and perfusion assessed by functional MRI in children with CF: reproducibility in comparison to lung function

BACKGROUND

Chronic lung diseases such as cystic fibrosis (CF) can be monitored by imaging and lung function modalities. Magnetic resonance imaging (MRI) techniques such as matrix pencil (MP) decomposition allows for evaluation of regional impairment of fractional ventilation (R_FV) and relative perfusion (R_Q). However, reproducibility of MP MRI outcomes in children with CF is unknown. We examined short-term variability of ventilation and perfusion impairment from MP MRI and compared this to lung function outcomes.

METHOD

Twenty-threeCF and 12 healthy school-aged children underwent MRI and lung function tests on the same day on two occasions 24 h apart. Global ventilation inhomogeneity was assessed by the lung clearance index (LCI) from nitrogen-multiple breath washout (N₂-MBW) technique. Intra-class-coefficient (ICC), percentage change, and Bland-Altman limits of agreement were evaluated to assess reproducibility.

RESULTS

Sixty-nine measurements from MP MRI and N₂-MBW were performed. The ICC between two visits for R_FV, R_Q and LCI ranged between 0.60 and 0.90 in individuals with CF and healthy controls. In individuals with CF, percentage of change between the visits was 0.02% for R_FV, -1.11% for R_Q and 2.91% for LCI and limits of agreement between visits were - 4.3% and 3.9% for R_FV, -4.4% and 3.7% for R_Q, and -2.6 and 3.0 for LCI.

CONCLUSIONS

Functional imaging is reproducible and short-term changes in R_FV and R_Q greater than ±4.4% can be considered clinical meaningful. Very good short-term reproducibility, and easy application without the need for breathing maneuvers or contrast agent, makes MP MRI a promising surveillance method for CF.