Use of FEV1 in cystic fibrosis epidemiologic studies and clinical trials: A statistical perspective for the clinical researcher

Factors associated with pulmonary function decline of patients in the cystic fibrosis registry of Turkey: A retrospective cohort study

BACKGROUND

The decline in pulmonary function is a predictor of disease progression in patients with cystic fibrosis (CF). This study aimed to determine the decline rate of percent predicted forced expiratory volume in 1 s (ppFEV1) based on the data of the CF Registry of Turkey. The secondary aim was to investigate the risk factors related to the decline in ppFEV1.

METHODS

A retrospective cohort study of CF patients over 6 years old, with pulmonary function data over at least 2 years of follow-up was extracted from the national CF registry for years 2017-2019. Patients were classified according to disease severity and age groups. Multivariate analysis was used to predict the decline in ppFEV1 and to investigate the associated risk factors.

RESULTS

A total of 1722 pulmonary function test results were available from 574 patients over the study period. Mean diagnostic age was older and weight for age, height for age, and body mass index z scores were significantly lower in the group of ppFEV1 < 40, while chronic Pseudomonas aeruginosa (p < .001) and mucoid P. aeruginosa colonization (p < .001) were significantly higher in this group (p < .001). Overall mean annual ppFEV1 decline was -0.97% (95% confidence interval [CI] = -0.02 to -1.92%). The mean change of ppFEV1 was significantly higher in the group with ppFEV1 ≥ 70 compared with the other (ppFEV1 < 40 and ppFEV1: 40-69) two groups (p = .004). Chronic P. aeruginosa colonization (odds ratio [OR] = 1.79 95% CI = 1.26-2.54; p = .01) and initial ppFEV1 ≥ 70 (OR = 2.98 95% CI = 1.06-8.36), p = .038) were associated with significant ppFEV1 decline in the whole cohort.

CONCLUSIONS

This data analysis recommends close follow-up of patients with normal initial ppFEV1 levels at baseline; advocates for early interventions for P. aeruginosa; and underlines the importance of nutritional interventions to slow down lung disease progression.

Impact of COVID-19 infection on lung function and nutritional status amongst individuals with cystic fibrosis: A global cohort study

BACKGROUND

Factors associated with severe COVID-19 infection have been identified; however, the impact of infection on longer-term outcomes is unclear. The objective of this study was to examine the impact of COVID-19 infection on the trajectory of lung function and nutritional status in people with cystic fibrosis (pwCF).

METHODS

This is a retrospective global cohort study of pwCF who had confirmed COVID-19 infection diagnosed between January 1, 2020 and December 31, 2021. Forced expiratory volume in one second percent predicted (ppFEV1) and body mass index (BMI) twelve months prior to and following a diagnosis of COVID-19 were recorded. Change in mean ppFEV1 and BMI were compared using a t-test. A linear mixed-effects model was used to estimate change over time and to compare the rate of change before and after infection.

RESULTS

A total of 6,500 cases of COVID-19 in pwCF from 33 countries were included for analysis. The mean difference in ppFEV1 pre- and post-infection was 1.4 %, (95 % CI 1.1, 1.7). In those not on modulators, the difference in rate of change pre- and post-infection was 1.34 %, (95 % CI -0.88, 3.56) per year (p = 0.24) and -0.74 % (-1.89, 0.41) per year (p = 0.21) for those on elexacaftor/tezacaftor/ivacaftor. No clinically significant change was noted in BMI or BMI percentile before and after COVID-19 infection.

CONCLUSIONS

No clinically meaningful impact on lung function and BMI trajectory in the year following infection with COVID-19 was identified. This work highlights the ability of the global CF community to unify and address critical issues facing pwCF.

Impact of day-to-day variation in FEV1 on measures of change: A conceptual description

Clinical trials often demonstrate treatment efficacy through change in forced expiratory volume in one second (FEV1), comparing single FEV1 measurements from post- versus pre-treatment timepoints. Day-to-day variation in measured FEV1 is common for reasons such as diurnal variation and intermittent health changes, relative to a stable, monthly average. This variation can alter estimation of associations between change in FEV1 and baseline in predictable ways, through a phenomenon called regression to the mean. We quantify and explain day-to-day variation in percent-predicted FEV1 (ppFEV1) from 4 previous trials, and we present a statistical, data-driven explanation for potential bias in ceiling and floor effects due to commonly observed amounts of variation. We recommend accounting for variation when assessing associations between baseline value and change in CF outcomes in single-arm trials, and we consider possible impact of variation on conventional standards for study eligibility.

Assessing the health impacts of parenthood on people with cystic fibrosis: the HOPeCF prospective cohort protocol

INTRODUCTION

People with cystic fibrosis (CF) are living longer and healthier lives with a growing number considering and pursuing parenthood. The decision of whether to become a parent is complex for people with CF, and CF is a major factor in reproductive decision-making. Unfortunately, in people with CF who become parents, there are no prospective studies of disease trajectory, no data on the impact of parenthood on mental health, disease self-management, or quality of life, and no research regarding non-genetic parenthood.

METHODS AND ANALYSIS

Health Outcomes of Parents with CF (HOPeCF) is a prospective, multicentre observational cohort study which will enrol 146 new parents with CF of children less than 5 years of age. The primary aim of this 60-month study is to assess the rate of lung function decline as impacted by mental health, parental stress and responsibility, and the use of CF transmembrane conductance regulator modulators. In addition, we will conduct dyadic interviews with a subset of study participants and their key supports (partner/family/friend) to inform future interventions.

ETHICS AND DISSEMINATION

This longitudinal, observational multicentre study is a necessary and timely step in understanding parental health outcomes in CF and will provide data essential for care guidance to people with CF, their partners, and healthcare providers. The University of Pittsburgh Institutional Review Board approved this study (STUDY23080161). As people with a variety of paediatric-onset chronic diseases are living longer and considering parenthood, these results may have widespread applicability and will be distributed at international meetings and submitted to peer-reviewed journals.

The impact of elexacaftor/tezacaftor/ivacaftor on cystic fibrosis health-related quality of life and decision-making about daily treatment regimens: a mixed methods exploratory study

Background

Elexacaftor/tezacaftor/ivacaftor (ETI) has reduced many symptoms of cystic fibrosis (CF).

Objectives

We sought to identify the impact of ETI on both symptoms and treatment decisions among adults with CF.

Design

Participants were enrolled in a cross-sectional study. Surveys were sent via a RedCap link. Semistructured interviews were administered remotely via Microsoft Teams. Interviews were audio recorded and professionally transcribed.

Methods

We assessed Cystic Fibrosis Questionnaire-Revised (CFQ-R) subscales for physical, respiratory, emotion, and treatment, and analyzed semistructured interviews covering CF treatment regimens and daily living. Quantitative and qualitative results were analyzed separately and via a mixed-methods convergence coding matrix.

Results

Twenty-four adults with CF taking ETI were included. CFQ-R subscale scores (mean scores/standard deviation) were physical (82.1/22.8), respiratory (83.7/11.2), emotion (65.3/14.2), and treatment (57.5/20.1). Three themes about decision-making for non-ETI-treatments emerged: (1) How I'm feeling, (2) Not noticing a difference, and (3) Uncertainty about long-term impact of modifying treatment regimens, and we found participants weighed each of these factors in their treatment decisions. Key findings from mixed-methods analysis show that among individuals experiencing higher CFQ-R scores for physical and respiratory compared to emotion and treatment, there were statements indicating that while those participants were experiencing better physical health, many continued their burdensome treatment regimens.

Conclusion

With little long-term data on the impact of reducing non-ETI treatments, participants weighed how they were feeling, treatment efficacy beliefs, and risk tolerance when making treatment decisions.

Close monitoring and early intervention: management principles for cystic fibrosis in Denmark

Cystic fibrosis (CF) care in Denmark has been characterized by close monitoring and pre-emptive treatment of lung disease and other CF-related complications. Continuous evaluation through data collection and commitment to clinical research has incrementally improved outcomes. This approach has been in line with best practices set forth by European Standards of Care but has also gone beyond Society standards particularly pertaining to early treatment with high-dose combination antimicrobial therapy. Despite a high prevalence of severe CF variants, lung function has been among the best in Europe. In this review, the Danish approach to management of CF prior to the introduction of new CF modulator treatment is explained and benchmarked. Downsides to the Danish approach are discussed and include increased burden of treatment, risk of antimicrobial resistance, side-effects and costs.

Cystic fibrosis in Europe: improved lung function and longevity - reasons for cautious optimism, but challenges remain

BACKGROUND

Prognosis and disease severity in cystic fibrosis (CF) are linked to declining lung function. To characterise lung function by the number of adults in countries with different levels of Gross National Income (GNI), data from the European Cystic Fibrosis Society Patient Registry were utilised.

METHODS

Annual data including age, forced expiratory volume in 1 s (FEV1), anthropometry, genotype, respiratory cultures and CF-related diabetes (CFRD) were retrieved between 2011 and 2021. All countries were stratified into GNI per capita to reflect differences within Europe.

RESULTS

A consistent improvement in FEV1 % pred and survival was observed among the 47 621 people with CF (pwCF), including subjects with chronic Pseudomonas aeruginosa infection, CFRD and/or undernutrition. Mean values of FEV1 % pred changed from 85% to 94.2% for children and from 63.6% to 74.7% for adults. FEV1 % pred further increased among those carrying the F508del mutation in 2021, when elexacaftor/tezacaftor/ivacaftor was available. The number of adult pwCF increased from 13 312 in 2011 to 21 168 in 2021, showing a 60% increase. PwCF living in European lower income countries did not demonstrate a significant annual increase in FEV1 % pred or in the number of adults.

CONCLUSION

This pan-European analysis demonstrates a consistent improvement in FEV1 % pred, number of adult pwCF and survival over the last decade only in European higher and middle income countries. Urgent action is needed in the lower income countries where such improvement was not observed. The notable improvement observed in pwCF carrying the F508del mutation emphasises the need to develop treatments for all CF mutations.

Development of the Addenbrooke's MSK screening tool (AMST) for children and adolescents with cystic fibrosis

Background

Musculoskeletal (MSK) issues are common in the paediatric population and in people with CF. There is currently no MSK screening tool for children and adolescents with CF.

Methods

The protocol to develop the pGALS (paediatric Gait, Arms, Legs, Spine) was followed to create this screening tool. Paediatric respiratory and MSK physiotherapists, and paediatric respiratory doctors at a large teaching hospital were involved in the creation of this tool. This was then reviewed by paediatric respiratory doctors and physiotherapists at a second large teaching hospital with amendments added. One year data of this screening tool used on children over 7 was collected and analysed as a secondary outcome of this project.

Results

There were 81.8 % more positive screens for MSK issues in the newly developed screening tool compared to the year using Manchester MSK screening tool; there were also 6 more referrals all deemed as appropriate by the services referred to. Almost half of the population screened using the developed tool were positive for an MSK issue, this was commonly related to poor posture or correctable kyphosis. Kyphosis, as measured by plumb line, appeared to be associated with negative health outcomes in this population; pectoralis major length was also associated with kyphosis and these negative health outcomes.

Conclusion

The development of this tool has followed the protocol set out by the PGALs and has shown some promise with interesting initial results. This tool will need further validation before it is used in the wider paediatric CF population.

Mucus Structure, Viscoelastic Properties, and Composition in Chronic Respiratory Diseases

The respiratory mucus, a viscoelastic gel, effectuates a primary line of the airway defense when operated by the mucociliary clearance. In chronic respiratory diseases (CRDs), such as asthma, chronic obstructive pulmonary disease (COPD), and cystic fibrosis (CF), the mucus is overproduced and its solid content augments, changing its structure and viscoelastic properties and determining a derangement of essential defense mechanisms against opportunistic microbial (virus and bacteria) pathogens. This ensues in damaging of the airways, leading to a vicious cycle of obstruction and infection responsible for the harsh clinical evolution of these CRDs. Here, we review the essential features of normal and pathological mucus (i.e., sputum in CF, COPD, and asthma), i.e., mucin content, structure (mesh size), micro/macro-rheology, pH, and osmotic pressure, ending with the awareness that sputum biomarkers (mucins, inflammatory proteins and peptides, and metabolites) might serve to indicate acute exacerbation and response to therapies. There are some indications that old and novel treatments may change the structure, viscoelastic properties, and biomarker content of sputum; however, a wealth of work is still needed to embrace these measures as correlates of disease severity in association with (or even as substitutes of) pulmonary functional tests.

Quantification of Enteric Dysfunction in Cystic Fibrosis: Inter- and Intraindividual Variability

OBJECTIVES

To test the utility of various biomarkers as indicators of gut dysfunction in cystic fibrosis (CF) and determine whether intraindividual variations in these measures are repeatable over short intervals and whether interindividual variations correlate with clinical outcomes.

STUDY DESIGN

We performed a cross-sectional, limited longitudinal study of children with CF aged 1-21 years who provided blood and stool samples at 2 or 3 visits, 2 weeks and 3 months apart, which were assayed for markers of intestinal inflammation (fecal calprotectin [fCal], lipocalin-2 [fLcn2], neopterin), and permeability (plasma lipopolysaccharide [LPS] antibodies, LPS-binding protein) by enzyme immunoassays. Control specimens were obtained from children without CF who had undergone esophagogastroduodenoscopy and had no evidence of gut inflammation.

RESULTS

Twenty-six of 29 participants with CF completed the study. Sixty-nine stools (57 case/12 control) and 76 plasmas (60 case/16 control) were analyzed. LPS antibody had reliable intraindividual stability. fCal, fLcn2, and neopterin were significantly greater in CF than in control samples. fCal was negatively correlated with 3-month interval change (Δ) in weight-for-age z-score, body mass index/weight-for-length z-score, and forced expiratory volume in 1 second. fLcn2 was negatively correlated with FEV1 but not with anthropometrics. No marker correlated with Δbody mass index/weight-for-length z-score or ΔFEV1.

CONCLUSIONS

fLcn2 is elevated in people with CF and might predict worse interval pulmonary function. Expanded studies are warranted to test if fLcn2 correlates with changes in additional outcomes.

Epidemiology and impact of methicillin-sensitive Staphylococcus aureus with β-lactam antibiotic inoculum effects in adults with cystic fibrosis

Staphylococcus aureus is the most prevalent cystic fibrosis (CF) pathogen. Several phenotypes are associated with worsened CF clinical outcomes including methicillin-resistance and small-colony-variants. The inoculum effect (IE) is characterized by reduced β-lactam susceptibility when assessed at high inoculum. The IE associates with worse outcomes in bacteremia and other high-density infections, and may therefore be relevant to CF. The prevalence of IE amongst a CF cohort (age ≥18 years), followed from 2013 to 2016, was investigated. Yearly methicillin-sensitive S. aureus (MSSA) isolates were screened at standard (5 × 105 CFU/mL) and high (5 × 107 CFU/mL) inoculum against narrow-spectrum anti-Staphylococcal β-lactams and those with anti-pseudomonal activity common to CF. A ≥ 4-fold increase in minimum inhibitory concentration between standard and high inoculum defined IE. Isolates underwent blaZ sequencing and genotyping and were compared against published genomes. Fifty-six percent (99/177) of individuals had MSSA infection. MSSA was observed at ≥105 CFU/mL in 44.8% of entry sputum samples. The prevalence of the IE was 25.0%-cefazolin; 13.5%-cloxacillin; 0%-meropenem; 1.0%-cefepime; 5.2%-ceftazidime; and 34.4%-piperacillin-tazobactam amongst baseline MSSA isolates assessed. blaZ A associated with cefazolin IE (P = 0.0011), whereas blaZ C associated with piperacillin-tazobactam IE (P < 0.0001). Baseline demographics did not reveal specific risk factors for IE-associated infections, nor were long-term outcomes different. Herein, we observed the IE in CF-derived MSSA disproportionally for cefazolin and piperacillin-tazobactam and this phenotype strongly associated with underlying blaZ genotype. The confirmation of CF being a high density infection, and the identification of high prevalence of MSSA with IE in CF supports the need for prospective pulmonary exacerbation treatment studies to understand the impact of this phenotype.

Respiratory system parameters in children with low severity cystic fibrosis: is there early involvement in relation to healthy peers?

OBJECTIVE

To compare and analyze pulmonary function and respiratory mechanics parameters between healthy children and children with cystic fibrosis.

METHODS

This cross-sectional analytical study included healthy children (HSG) and children with cystic fibrosis (CFG), aged 6-13 years, from teaching institutions and a reference center for cystic fibrosis in Florianópolis/SC, Brazil. The patients were paired by age and sex. Initially, an anthropometric evaluation was undertaken to pair the sample characteristics in both groups; the medical records of CFG were consulted for bacterial colonization, genotype, and disease severity (Schwachman-Doershuk Score - SDS) data. Spirometry and impulse oscillometry were used to assess pulmonary function.

RESULTS

In total, 110 children were included, 55 in each group. In the CFG group, 58.2% were classified as excellent by SDS, 49.1% showed the ΔF508 heterozygotic genotype, and 67.3% were colonized by some pathogens. Statistical analysis revealed significant differences between both groups (p<0.05) in most pulmonary function parameters and respiratory mechanics.

CONCLUSIONS

Children with cystic fibrosis showed obstructive ventilatory disorders and compromised peripheral airways compared with healthy children. These findings reinforce the early changes in pulmonary function and mechanics associated with this disease.

Bayesian causal inference for observational studies with missingness in covariates and outcomes

Missing data are a pervasive issue in observational studies using electronic health records or patient registries. It presents unique challenges for statistical inference, especially causal inference. Inappropriately handling missing data in causal inference could potentially bias causal estimation. Besides missing data problems, observational health data structures typically have mixed-type variables - continuous and categorical covariates - whose joint distribution is often too complex to be modeled by simple parametric models. The existence of missing values in covariates and outcomes makes the causal inference even more challenging, while most standard causal inference approaches assume fully observed data or start their works after imputing missing values in a separate preprocessing stage. To address these problems, we introduce a Bayesian nonparametric causal model to estimate causal effects with missing data. The proposed approach can simultaneously impute missing values, account for multiple outcomes, and estimate causal effects under the potential outcomes framework. We provide three simulation studies to show the performance of our proposed method under complicated data settings whose features are similar to our case studies. For example, Simulation Study 3 assumes the case where missing values exist in both outcomes and covariates. Two case studies were conducted applying our method to evaluate the comparative effectiveness of treatments for chronic disease management in juvenile idiopathic arthritis and cystic fibrosis.

Pulmonary Function and Quality of Life in Adults with Cystic Fibrosis

PURPOSE

People living with cystic fibrosis (CF) experience impaired quality of life, but the extent to which pulmonary function is associated with quality of life in CF remains unclear METHODS: Using baseline data from a trial of specialist palliative care in adults with CF, we examined the association between pulmonary obstruction and quality of life (measured with the Functional Assessment of Chronic Illness Therapy Total Score).

RESULTS

Among 262 participants, median age was 33, and 78% were on modulator therapy. The median quality of life score was higher in those with mild obstruction (135, IQR 110-156) compared to moderate (125, IQR 109-146) and severe obstruction (120, IQR 106-136). In an unadjusted model, we observed a non-significant trend toward lower quality of life with increased obstruction-compared to participants with mild obstruction, those with moderate obstruction had quality of life score 7.46 points lower (95% CI -15.03 to 0.10) and those with severe obstruction had a score 9.98 points lower (95% CI -21.76 to 1.80). However, this association was no longer statistically significant in the adjusted model, which may reflect confounding due to sex, age, BMI, and modulator therapy. Comorbidities (depression and anxiety) and social determinants of health (financial insecurity and education) were also associated with quality of life.

CONCLUSION

Advancing our understanding of patient-centered markers of quality of life, rather than focusing on pulmonary function alone, may help identify novel interventions to improve quality of life in this patient population.

Low-frequency oscillometry indices to assess ventilation inhomogeneity in CF patients

BACKGROUND

The utility of the forced oscillations technique (FOT) in cystic fibrosis (CF) remains uncertain. The aim of this study was to explore the ability of lower-frequency FOT indices, alone and after adjustment for the lung volume, to assess the extent of ventilation inhomogeneity in CF patients with varying disease severity.

METHODS

Forty-five children, adolescents, and adults with CF (age 6.9-27 years) underwent spirometry, FOT, and nitrogen multiple-breath washout (N2-MBW) measurements. The respiratory resistance and reactance at 5 Hz (Rrs5 and Xrs5, respectively) were recorded, and a novel FOT index, the specific respiratory conductance (sGrs), was computed as the reciprocal of Rrs5 divided by the functional residual capacity.

RESULTS

The sGrs correlated well with the lung clearance index (LCI) (Spearman's r: -.797), whereas the correlation of Rrs5 and Xrs5 with the LCI, albeit significant, was weaker (r: .643 and -.631, respectively). The sGrs emerged as the most robust predictor of LCI regardless of the severity of lung disease, as reflected by patients' age and lung function measurements. Most importantly, the relationship between sGrs and LCI remained unaffected by lung hyperinflation, as opposed to that of the LCI with the spirometric and standard FOT indices.

CONCLUSIONS

In CF patients, the FOT indices at 5 Hz and the novel, volume-adjusted parameter sGrs, reflect the extent of lung involvement and the underlying ventilation inhomogeneity in a way comparable to N2-MBW. Future research should explore the role of lower-frequency FOT in assessing the severity and monitoring the progression of CF lung disease.

Human epididymis protein 4 (HE4) plasma concentration inversely correlates with the improvement of cystic fibrosis lung disease in p.Phe508del-CFTR homozygous cases treated with the CFTR modulator lumacaftor/ivacaftor combination

BACKGROUND

We previously documented that elevated HE4 plasma concentration decreased in people with CF (pwCF) bearing the p.Gly551Asp-CFTR variant in response to CFTR modulator (CFTRm) ivacaftor (IVA), and this level was inversely correlated with the FEV1% predicted values (ppFEV1). Although the effectiveness of lumacaftor (LUM)/IVA in pwCF homozygous for the p.Phe508del-CFTR variant has been evaluated, plasma biomarkers were not used to monitor treatment efficacy thus far.

METHODS

Plasma HE4 concentration was examined in 68 pwCF drawn from the PROSPECT study who were homozygous for the p.Phe508del-CFTR variant before treatment and at 1, 3, 6 and 12 months after administration of LUM/IVA therapy. Plasma HE4 was correlated with ppFEV1 using their absolute and delta values. The discriminatory power of delta HE4 was evaluated for the detection of lung function improvements based on ROC-AUC analysis and multiple regression test.

RESULTS

HE4 plasma concentration was significantly reduced below baseline following LUM/IVA administration during the entire study period. The mean change of ppFEV1 was 2.6% (95% CI, 0.6 to 4.5) by 6 months of therapy in this sub-cohort. A significant inverse correlation between delta values of HE4 and ppFEV1 was observed especially in children with CF (r=-0.7053; p<0.0001). Delta HE4 predicted a 2.6% mean change in ppFEV1 (AUC: 0.7898 [95% CI 0.6823-0.8972]; P < 0.0001) at a cut-off value of -10.7 pmol/L. Moreover, delta HE4 independently represented the likelihood of being a responder with ≥ 5% delta ppFEV1 at 6 months (OR: 0.89, 95% CI: 0.82-0.95; P = 0.001).

CONCLUSIONS

Plasma HE4 level negatively correlates with lung function improvement assessed by ppFEV1 in pwCF undergoing LUM/IVA CFTRm treatment.

Reducing unnecessary testing on sputum specimens from patients with cystic fibrosis: pathology stewardship in microbiology

Chronic respiratory tract infection by Pseudomonas aeruginosa is the hallmark of established lung disease in patients with cystic fibrosis (CF). Antibiotic therapy can usually only suppress but not eradicate infection. In recent years, pulmonary infection with non-tuberculous Mycobacteria (NTM) species has also been increasing. These patients are often colonised with multiple isolates and determination of clinical significance of each isolate is difficult. The clinical value of frequent routine susceptibility testing of individual isolates is unproven, particularly since a delay in susceptibility testing is inevitable when purification of multiple cultured isolates is required to test each isolate separately. From August 2019 until December 2020 we ceased routine susceptibility testing on P. aeruginosa respiratory tract isolates from patients with CF if a previous isolate from the patient had susceptibility testing performed. We found that the proportion of P. aeruginosa isolates that had susceptibility testing performed dropped from 97% to 11% as a result of this change in laboratory process. During this time, we also ceased routine culture for acid-fast bacilli if this had been performed within the previous 6 months. We present the cost and resource savings for these changes in laboratory process and assess for clinical impact measured as hospital admissions, length of stay in hospital and mortality.

Dynamic Hyperinflation While Exercising-A Potential Predictor of Pulmonary Deterioration in Cystic Fibrosis

BACKGROUND

Lung function deterioration in cystic fibrosis (CF) is typically measured by a decline in the forced expiratory volume in one second (FEV1%), which is thought to be a late marker of lung disease. Dynamic hyperinflation (DH) is seen in obstructive lung diseases while exercising. Our aim was to assess whether DH could predict pulmonary deterioration in CF; a secondary measure was the peak VO2.

METHODS

A retrospective study was conducted of people with CF who performed cardiopulmonary exercise tests (CPETs) during 2012-2018. The tests were classified as those demonstrating DH non-DH. Demographic, genetic, and clinical data until 12.2022 were extracted from patient charts.

RESULTS

A total of 33 patients aged 10-61 years performed 41 valid CPETs with valid DH measurements; sixteen (39%) demonstrated DH. At the time of the CPETs, there was no difference in the FEV1% measurements between the DH and non-DH groups (median 83.5% vs. 87.6%, respectively; p = 0.174). The FEV1% trend over 4 years showed a decline in the DH group compared to the non-DH group (p = 0.009). A correlation was found between DH and the lung clearance index (LCI), as well as the FEV1% (r = 0.36 and p = 0.019 and r = -0.55 and p = 0.004, respectively). Intravenous (IV) antibiotic courses during the 4 years after the CPETs were significantly more frequent in the DH group (p = 0.046). The peak VO2 also correlated with the FEV1% and LCI (r = 0.36 and p = 0.02 and r = -0.46 and p = 0.014, respectively) as well as with the IV antibiotic courses (r = -0.46 and p = 0.014).

CONCLUSIONS

In our cohort, the DH and peak VO2 were both associated with lung function deterioration and more frequent pulmonary exacerbations. DH may serve as a marker to predict pulmonary deterioration in people with CF.

Association of Pseudomonas aeruginosa infection stage with lung function trajectory in children with cystic fibrosis

BACKGROUND

Pseudomonas aeruginosa (Pa) infection in cystic fibrosis (CF) is characterized in stages: never (prior to first positive culture) to incident (first positive culture) to chronic. The association of Pa infection stage with lung function trajectory is poorly understood and the impact of age on this association has not been examined. We hypothesized that FEV1 decline would be slowest prior to Pa infection, intermediate after incident infection and greatest after chronic Pa infection.

METHODS

Participants in a large US prospective cohort study diagnosed with CF prior to age 3 contributed data through the U.S. CF Patient Registry. Cubic spline linear mixed effects models were used to evaluate the longitudinal association of Pa stage (never, incident, chronic using 4 different definitions) with FEV1 adjusted for relevant covariates. Models contained interaction terms between age and Pa stage.

RESULTS

1,264 subjects born 1992-2006 provided a median 9.5 (IQR 0.25 to 15.75) years of follow up through 2017. 89% developed incident Pa; 39-58% developed chronic Pa depending on the definition. Compared to never Pa, incident Pa infection was associated with greater annual FEV1 decline and chronic Pa infection with the greatest FEV1 decline. The most rapid FEV1 decline and strongest association with Pa infection stage was seen in early adolescence (ages 12-15).

CONCLUSIONS

Annual FEV1 decline worsens significantly with each Pa infection stage in children with CF. Our findings suggest that measures to prevent chronic infection, particularly during the high-risk period of early adolescence, could mitigate FEV1 decline and improve survival.

Associations between spirometric measures and exercise capacity in type 2 diabetes

BACKGROUND

Physical exercise aids glycemic control and the prevention of diabetes-related complications. However, exercise beyond an individual's pulmonary functional capacity may be detrimental. To date, little is known about the relationship between pulmonary function and exercise capacity in people with type 2 diabetes (T2D). We investigated the relationship between pulmonary function and exercise capacity in T2D.

METHODS

Spirometry and 6-min walk test (6MWT) were conducted for 263 systematically sampled adults with T2D without primary heart/lung disease. The primary measure of exercise capacity was the 6-min walk distance (6MWD); impaired exercise capacity was defined as 6MWD<400 m. Logistic regression analyses were used to assess the associations between spirometric measures and exercise capacity with adjustments for age, sex, height, body mass index, diabetes duration, glycated hemoglobin concentration, smoking, suboptimum blood pressure control, and total cholesterol concentration.

RESULTS

Compared with individuals with normal spirometry, those with pulmonary restriction/obstruction had significantly lower 6MWD (404.67 m vs. 451.70),p < 0.001). The proportion of individuals with impaired exercise capacity was higher in individuals with impaired pulmonary function compared with those with normal pulmonary function (39.8% vs. 20.7%,p = 0.001). In the unadjusted models, decreasing Z-score FEV1 [odds ratio 1.40, 95% confidence interval (1.07-1.83),p = 0.013] and Z-score FVC [1.37 (1.06-1.76),0.016], but not Z-score FEV1/FVC ratio [1.00 (0.78-1.27),0.972] were significantly associated with impaired exercise capacity. In the fully adjusted model, the strength of association remained statistically significant for Z-score FEV1 [1.60 (1.06-2.41),0.025] but not Z-score FVC [1.48 (0.98-2.23),0.065].

CONCLUSIONS

Our study shows inverse associations between FEV1 and impaired exercise capacity in T2D, Future research could characterize optimal exercise levels based on a patient's FEV1.

Association between nebuliser therapies adherence and visit-to-visit variability of FEV1 in patients with cystic fibrosis

At the same level of lung function, some patients with cystic fibrosis have large variations in their FEV1 percent predicted (FEV1pp) values while others have stable values. We hypothesised that lower adherence to nebuliser therapies was associated with higher FEV1pp variability. We conducted a post hoc analysis of the ACtiF trial data. Adherence was calculated using data from data-logging nebulisers, and FEV1pp variability using the coefficient of variation equation. Amongst the 543 patients included in the analysis, those poorly adherent (adherence < 50%) had a higher FEV1pp variability than patients moderately (50 to < 80%) and highly adherent (≥ 80%), with median values (IQR1-3) of 8.1% (4.9-13.7), 6.3% (3.9-9.8), and 6.3% (3.9-9.3) respectively (p < 0.01). This result was confirmed by a multiple linear regression including adherence as a continuous variable (p < 0.01). Further studies are needed to determine the implications of these differences in FEV1pp variability on the prognosis of patients.

Lung Function Decline in Cystic Fibrosis: Impact of Data Availability and Modeling Strategies on Clinical Interpretations

Rationale: Studies estimating the rate of lung function decline in cystic fibrosis have been inconsistent regarding the methods used. How the methodology used impacts the validity of the results and comparability between studies is unknown. Objectives: The Cystic Fibrosis Foundation established a work group whose tasks were to examine the impact of differing approaches to estimating the rate of decline in lung function and to provide analysis guidelines. Methods: We used a natural history cohort of 35,252 individuals with cystic fibrosis aged ⩾6 years in the Cystic Fibrosis Foundation Patient Registry (CFFPR), 2003-2016. Modeling strategies using linear and nonlinear forms of marginal and mixed-effects models, which have previously quantified the rate of forced expiratory volume in 1 second (FEV1) decline (percent predicted per year), were evaluated under clinically relevant scenarios of available lung function data. Scenarios varied by sample size (overall CFFPR, medium-sized cohort of 3,000 subjects, and small-sized cohort of 150), data collection/reporting frequency (encounter, quarterly, and annual), inclusion of FEV1 during pulmonary exacerbation, and follow-up length (<2 yr, 2-5 yr, entire duration). Results: Rate of FEV1 decline estimates (percent predicted per year) differed between linear marginal and mixed-effects models; overall cohort estimates (95% confidence interval) were 1.26 (1.24-1.29) and 1.40 (1.38-1.42), respectively. Marginal models consistently estimated less rapid lung function decline than mixed-effects models across scenarios, except for short-term follow-up (both were ∼1.4). Rate of decline estimates from nonlinear models diverged by age 30. Among mixed-effects models, nonlinear and stochastic terms fit best, except for short-term follow-up (<2 yr). Overall CFFPR analysis from a joint longitudinal-survival model implied that an increase in rate of decline of 1% predicted per year in FEV1 was associated with a 1.52-fold (52%) increase in the hazard of death/lung transplant, but the results exhibited immortal cohort bias. Conclusions: Differences were as high as 0.5% predicted per year between rate of decline estimates, but we found estimates were robust to lung function data availability scenarios, except short-term follow-up and older age ranges. Inconsistencies among previous study results may be attributable to inherent differences in study design, inclusion criteria, or covariate adjustment. Results-based decision points reported herein will support researchers in selecting a strategy to model lung function decline most reflective of nuanced, study-specific goals.

Factors associated with frequent high-cost individuals with cystic fibrosis and their healthcare utilization and cost patterns

Cystic fibrosis (CF) is a progressive multi-organ disease with significant morbidity placing extensive demands on the healthcare system. Little is known about those individuals with CF who continually incur high costs over multiple years. Understanding their characteristics may help inform opportunities to improve management and care, and potentially reduce costs. The purpose of this study was to identify and understand the clinical and demographic attributes of frequent high-costing CF individuals and characterize their healthcare utilization and costs over time. A longitudinal study of retrospective data was completed in British Columbia, Canada by linking the Canadian CF Registry with provincial healthcare administrative databases for the period between 2009 and 2017. Multivariable Cox regression models were employed to identify baseline factors associated with becoming a frequent high-cost CF user (vs. not a frequent high-cost CF user) in the follow-up period. We found that severe lung impairment (Hazard Ratio [HR]: 3.71, 95% confidence interval [CI], 1.49-9.21), lung transplantation (HR: 4.23, 95% CI, 1.68-10.69), liver cirrhosis with portal hypertension (HR: 10.96, 95% CI: 3.85-31.20) and female sex (HR: 1.97, 95% CI: 1.13-3.44) were associated with becoming a frequent high-cost CF user. Fifty-nine (17% of cohort) frequent high-cost CF users accounted for more than one-third of the overall total healthcare costs, largely due to inpatient hospitalization and outpatient medication costs.

Serum Appetite-Regulating Hormone Levels in Cystic Fibrosis Patients: Influence of the Disease Severity and the Type of Bacterial Infection-A Pilot Study

Cystic fibrosis (CF) belongs to the most common inherited diseases. The severity of the disease and chronic bacterial infections are associated with a lower body index, undernutrition, higher number of pulmonary exacerbations, more hospital admissions, and increased mortality. The aim of our study was to determine the impact of the severity of the disease and the type of bacterial infection in 38 CF patients on the serum level of appetite-regulating hormones including leptin, ghrelin, neuropeptide Y, agouti-signaling protein, proopiomelanocortin, kisspeptin, putative protein Y, and α-melanocyte-stimulating hormone. The patients were divided according to the severity of the disease according to spirometry and the type of chronic bacterial infection. We found that leptin level was significantly higher in patients with severe CF than in patients with mild disease (20.02 ± 8.09 vs. 12.38 ± 6.03 ng/mL, p = 0.028). Furthermore, leptin level was elevated in patients with chronic infection with Pseudomonas aeruginosa compared to uninfected participants (15.74 ± 7.02 vs. 9.28 ± 1.72 ng/mL, p = 0.043). The severity of the disease and the type of bacterial infection did not affect the levels of other appetite-regulating hormones. Moreover, we found a positive correlation between pro-inflammatory interleukin-6 and leptin level (p = 0.0426, R = 0.333). Taken together, our results indicate that both the severity of the disease and the type of bacterial infection are associated with elevated leptin levels in CF patients. Future CF treatment strategies should consider possible disturbances in the hormones that regulate appetite and the factors that influence their levels.

Systematic review and meta-analysis: Associations of vitamin D with pulmonary function in children and young people with cystic fibrosis

BACKGROUND

Increasing evidence suggests that vitamin D is associated with pulmonary health, which may benefit children and young people diagnosed with Cystic Fibrosis (cypCF). Therefore, the aim of this systematic review was to evaluate primary research to establish associations between 25OHD and pulmonary health in cypCF.

METHODS

Electronic databases were searched with keywords related to CF, vitamin D, children/young people and pulmonary function. Included studies were cypCF (aged ≤21 years) treated in a paediatric setting. The primary outcome was lung function [forced expiratory volume in 1 s (FEV₁% predicted)] and secondary outcomes were rate of pulmonary exacerbations, 25OHD status and growth. Evidence was appraised for risk of bias using the CASP tool, and quality using the EPHPP tool. A Meta-analysis was performed.

RESULTS

Twenty-one studies were included with mixed quality ratings and heterogeneity of reported outcomes. The Meta-analysis including 5 studies showed a significantly higher FEV₁% predicted in the 25OHD sufficiency compared to the deficiency group [FEV₁% predicted mean difference (95% CI) was 7.71 (1.69-13.74) %; p = 0.01]. The mean ± SD FEV₁% predicted for the sufficient (≥75 nmol/L) vs. deficient (<50 nmol/L) group was 94.7 ± 31.9% vs. 86.9 ± 13.2%; I² = 0%; χ² = 0.5; df = 4). Five studies (5/21) found significantly higher rate of pulmonary exacerbations in those who were 25OHD deficient when compared to the sufficient group and negative associations between 25OHD and FEV% predicted. The effects of vitamin D supplementation dosages on 25OHD status (10/21) varied across studies and no study (12/21) showed associations between 25OHD concentration and growth.

CONCLUSION

This systematic review suggests that 25OHD concentration is positively associated with lung function and a concentration of >75 nmol/L is associated with reduced frequency of pulmonary exacerbations, which may slow lung function decline in cypCF. Future randomised clinical trials and mechanistic studies are warranted.

Efficacy of hypertonic saline versus isotonic saline among children with cystic fibrosis: A systematic review and meta-analysis

Background

Inhaled hypertonic saline (HS) reduces pulmonary exacerbations in patients with cystic fibrosis (CF) aged 6 or more years. However, the effectiveness of HS in improving clinical outcomes in younger children aged 6 or less years is not established. This study examines the efficacy of HS in younger CF patients.

Methods

Searches were conducted across three databases (Medline, Cochrane Central and EMBASE) from inception through July 2022. Randomized controlled trials assessing the impact of HS in younger CF patients were included. Trials involving only patients greater than 6 years or control group other than isotonic saline (IS) were excluded. Outcomes measured included lung clearance index (LCI), cystic fibrosis questionnaire (CFQ-R) score, spirometry measures, oxygen saturation, respiratory rate, height and weight. Outcomes were reported as mean differences (MDs) with 95% confidence intervals.

Results

Seven studies (n = 390 patients) were included in this review. HS significantly reduced the LCI (MD: -0.67; 95%CI, -1.05 to 0.29, P = 0.0006) compared to IS. In addition, HS was associated with significant improvements in height (MD: 2.23; 95%CI, -0.00 to 4.46, P = 0.05) and CFQ-R (MD: 4.30; 95%CI, 0.65-7.95, P = 0.02), but not in oxygen saturation (MD: -0.15; 95%CI, -0.54 to 0.25, P = 0.47), respiratory rate (MD: -0.21; 95%CI, -2.19 to 1.77, P = 0.83) or weight (MD: 0.70; 95%CI, -0.47 to 1.87, P = 0.24). Furthermore, HS did not significantly improve spirometry measures, including FEV₁ (MD: -0.11; 95%CI, -0.21 to 0.43, P = 0.51) and forced vital capacity (MD: 0.27; 95%CI, -0.49 to 1.04, P = 0.48), but significantly improved FEF_25-75 (MD: 0.12; 95% CI, 0.05-0.20; P = 0.002).

Discussion

Treatment with HS in younger children with CF improves lung clearance, symptoms and quality of life. FEF_25-75 may prove a more sensitive measure for assessing intervention related improvements in pediatric CF trials.

Conclusion

The findings support HS as a therapeutic method in CF-affected children.

Evaluation of serum VIP and aCGRP during pulmonary exacerbation in cystic fibrosis: A longitudinal pilot study of patients undergoing antibiotic therapy

BACKGROUND

Objective monitoring of improvement during treatment of pulmonary exacerbation can be difficulty in children when pulmonary function testing cannot be obtained. Thus, the identification of predictive biomarkers to determine the efficacy of drug treatments is of high priority. The major aim of the current study was to investigate the serum levels of vasoactive intestinal peptide (VIP) and alpha calcitonin gene related peptide (aCGRP) of cystic fibrosis pediatric patients during pulmonary exacerbation and post-antibiotic therapy, and possible associations of their levels with different clinicopathological parameters.

METHODS

21 patients with cystic fibrosis were recruited at onset of pulmonary exacerbation. Serum was collected at time of admission, three days post-antibiotic therapy, and two weeks post-antibiotic therapy (end of antibiotic therapy). Serum VIP and aCGRP levels were measured using ELISA.

RESULTS

Overall least square means of serum aCGRP level but not VIP changed from time of exacerbation to completion of antibiotic therapy (p = 0.005). Serum VIP was significantly associated with the presence of diabetes mellitus (p = 0.026) and other comorbidities (p = 0.013), and with type of antibiotic therapy (p = 0.019). Serum aCGRP level was significantly associated with type of antibiotic therapy (p = 0.012) and positive Staphylococcus aureus microbiology test (p = 0.046).

CONCLUSION

This study could only show significant changes in serum aCGRP levels following treatment of pulmonary exacerbations. Future studies with larger sample size are required to investigate the clinical importance of VIP and aCGRP in cystic fibrosis patients.

Assessing the health risk of living near composting facilities on lung health, fungal and bacterial disease in cystic fibrosis: a UK CF Registry study

AIM

To explore the health risk of living near permitted composting sites (PCSs) on disease severity in children and adults with cystic fibrosis (CF) across the UK.  METHODS: A semi-individual cross-sectional study was used to examine the risk of disease severity in people with CF (pwCF) within and beyond 4 km of PCSs in the UK in 2016. All pwCF registered in the UK CF Registry were eligible for this study. Linear and Poisson regressions, adjusted for age, gender, genotype, BMI, Pseudomonas aeruginosa and deprivation, were used to quantify associations between distance to a PCS and percent predicted forced expiratory volume in one second (ppFEV₁), pulmonary exacerbations (#IVdays), and fungal and bacterial infections.

RESULTS

The mean age of the 9,361 pwCF (3,931 children and 5,430 adults) studied was 20.1 (SD = 14.1) years; 53.3% were male; and 49.2% were homozygous F508del. Over 10% of pwCF (n = 1,015) lived within 4 km of a PCS. We found no statistically significant difference in ppFEV₁ and #IVdays/year in children. However, in adults, ppFEV₁ was -1.07% lower (95% confidence interval (CI): -2.29%, 0.16%) and #IVdays/year were 1.02 day higher (95%CI: 1.01, 1.04) within 4 km of a PCS. Furthermore, there were statistically significant differences in mean ppFEV₁ in CF adults with Aspergillus fumigatus (58.2.% vs 62.0%, p = 0.005) and Candida spp. (56.9% vs 59.9%, p = 0.029) residing within 4 km of a PCS. No associations were identified for allergic bronchopulmonary aspergillosis, P. aeruginosa or Staphylococcus aureus.

CONCLUSIONS

This novel national study provides evidence that adults with CF living near a PCS may experience small reductions in lung function, an increased risk of pulmonary exacerbations, and more frequent fungal infections. If confirmed by studies using refined exposure assessment methods accounting for bioaerosol dispersion, these results could have important implications for the living environment of pwCF.

Treatment With LAU-7b Complements CFTR Modulator Therapy by Improving Lung Physiology and Normalizing Lipid Imbalance Associated With CF Lung Disease

Cystic fibrosis (CF) is the most common autosomal recessive genetic disease in Caucasians, affecting more than 100,000 individuals worldwide. It is caused by pathogenic variants in the gene encoding CFTR, an anion channel at the plasma membrane of epithelial and other cells. Many CF pathogenic variants disrupt the biosynthesis and trafficking of CFTR or reduce its ion channel function. The most frequent mutation, loss of a phenylalanine at position 508 (F508del), leads to misfolding, retention in the endoplasmic reticulum, and premature degradation of the protein. The therapeutics available for treating CF lung disease include antibiotics, mucolytics, bronchodilators, physiotherapy, and most recently CFTR modulators. To date, no cure for this life shortening disease has been found. Treatment with the Triple combination drug therapy, TRIKAFTA®, is composed of three drugs: Elexacaftor (VX-445), Tezacaftor (VX-661) and Ivacaftor (VX-770). This therapy, benefits persons with CF, improving their weight, lung function, energy levels (as defined by reduced fatigue), and overall quality of life. We examined the effect of combining LAU-7b oral treatment and Triple therapy combination on lung function in a F508deltm1EUR mouse model that displays lung abnormalities relevant to human CF. We assessed lung function, lung histopathology, protein oxidation, lipid oxidation, and fatty acid and lipid profiles in F508deltm1EUR mice.

The Presence of Exophiala dermatitidis in the Respiratory Tract of Cystic Fibrosis Patients Accelerates Lung Function Decline: A Retrospective Review of Lung Function

Exophiala dermatitidis is increasingly isolated from cystic fibrosis (CF) respiratory samples. The decision to treat is hampered by limited evidence demonstrating the clinical significance of isolating E. dermatitidis. The objective was to assess the impact of E. dermatitidis isolation on the lung function of CF patients. The rate of lung function decline in the local CF population was calculated using historic lung function data. A control population who had never had E. dermatitidis cultured from the respiratory tract was compared with the E. dermatitidis group, calculating their rate of lung function decline before and after the first isolation of the organism. A total of 1840 lung function measurements were reviewed between the 31 E. dermatitidis group patients and 62 control patients. Their demographics were similar. The control group declined at a rate of −0.824 FEV1%/year. The rate of decline in the E. dermatitidis group prior to infection was −0.337 FEV1%/year (p = 0.2). However, post infection with E. dermatitidis, there was a significant increase in the rate of decline in lung function (−1.824 FEV1%/year, p < 0.01). The results suggest E. dermatitidis has a temporal relationship with accelerated rate of lung function decline. It is not clear if this is a cause or effect, but this accelerated rate of decline indicates a need for further investigation.

CFTR-mediated monocyte/macrophage dysfunction revealed by cystic fibrosis proband-parent comparisons

Cystic fibrosis (CF) is an inherited disorder caused by biallelic mutations of the CF transmembrane conductance regulator (CFTR) gene. Converging evidence suggests that CF carriers with only 1 defective CFTR copy are at increased risk for CF-related conditions and pulmonary infections, but the molecular mechanisms underpinning this effect remain unknown. We performed transcriptomic profiling of peripheral blood mononuclear cells (PBMCs) of CF child-parent trios (proband, father, and mother) and healthy control (HC) PBMCs or THP-1 cells incubated with the plasma of these participants. Transcriptomic analyses revealed suppression of cytokine-enriched immune-related genes (IL-1β, CXCL8, CREM), implicating lipopolysaccharide tolerance in innate immune cells (monocytes) of CF probands and their parents. These data suggest that a homozygous as well as a heterozygous CFTR mutation can modulate the immune/inflammatory system. This conclusion is further supported by the finding of lower numbers of circulating monocytes in CF probands and their parents, compared with HCs, and the abundance of mononuclear phagocyte subsets, which correlated with Pseudomonas aeruginosa infection, lung disease severity, and CF progression in the probands. This study provides insight into demonstrated CFTR-related innate immune dysfunction in individuals with CF and carriers of a CFTR mutation that may serve as a target for personalized therapy.

An Adverse Outcome Pathway for Decreased Lung Function Focusing on Mechanisms of Impaired Mucociliary Clearance Following Inhalation Exposure

Adverse outcome pathways (AOPs) help to organize available mechanistic information related to an adverse outcome into key events (KEs) spanning all organizational levels of a biological system(s). AOPs, therefore, aid in the biological understanding of a particular pathogenesis and also help with linking exposures to eventual toxic effects. In the regulatory context, knowledge of disease mechanisms can help design testing strategies using in vitro methods that can measure or predict KEs relevant to the biological effect of interest. The AOP described here evaluates the major processes known to be involved in regulating efficient mucociliary clearance (MCC) following exposures causing oxidative stress. MCC is a key aspect of the innate immune defense against airborne pathogens and inhaled chemicals and is governed by the concerted action of its functional components, the cilia and airway surface liquid (ASL). The AOP network described here consists of sequences of KEs that culminate in the modulation of ciliary beat frequency and ASL height as well as mucus viscosity and hence, impairment of MCC, which in turn leads to decreased lung function.

Ultrasound-Derived Diaphragm Contractile Reserve as a Marker of Clinical Status in Patients With Cystic Fibrosis

Introduction: In patients with cystic fibrosis (CF), the monitoring of respiratory muscle activity using electromyography can provide information on the demand-to-capacity ratio of the respiratory system and act as a clinical marker of disease activity, but this technique is not adapted to routine clinical care. Ultrasonography of the diaphragm could provide an alternative, simpler and more widely available alternative allowing the real-time assessment of the diaphragm contractile reserve (DCR), but its relationship with recognized markers of disease severity and clinical outcomes are currently unknown.

Methods: Stable patients with CF were prospectively recruited. Diaphragm ultrasound was performed and compared to forced expiratory volume in 1 s (FEV₁), residual volume (RV), handgrip strength, fat-free mass index (FFMI), serum vitamin levels, dyspnea levels and rate of acute exacerbation (AE). Diaphragm activity was reported as DCR (the ratio of tidal-to-maximal thickening fractions, representing the remaining diaphragm contractility available after tidal inspiration) and TFmax (representing maximal diaphragm contractile strength). Inter-observer reliability of the measurement of DCR was evaluated using intra-class correlation analysis.

Results: 110 patients were included [61 males, median (interquartile range), age 31 (27–38) years, FEV₁ 66 (46–82)% predicted]. DCR was significantly correlated to FEV₁ (rho = 0.46, p < 0.001), RV (rho = −0.46, p < 0.001), FFMI (rho = 0.41, p < 0.001), and handgrip strength (rho = 0.22, p = 0.02), but TFmax was not. In a multiple linear regression analysis, both RV and FFMI were independent predictors of DCR. DCR, but not TFmax, was statistically lower in patients with > 2 exacerbations/year (56 ± 25 vs. 71 ± 17%, p = 0.001) and significantly lower with higher dyspnea levels. A ROC analysis showed that DCR performed better than FEV₁ (mean difference in AUROC 0.09, p = 0.04), RV (mean difference in AUROC 0.11, p = 0.03), and TFmax at identifying patients with an mMRC score > 2. Inter-observer reliability of DCR was high (ICC = 0.89, 95% CI 0.84–0.92, p < 0.001).

Conclusion: In patients with CF, DCR is a reliable and non-invasive marker of disease severity that is related to respiratory and extra-pulmonary manifestations of the disease and to clinical outcomes. Future studies investigating the use of DCR as a longitudinal marker of disease progression, response to interventions or target for therapy would further validate its translation into clinical practice.

Long-term, low-dose macrolide antibiotic treatment in pediatric chronic airway diseases

Macrolide antibiotics are one of the most commonly used broad-spectrum antibiotics. They have an inhibitory effect on a variety of respiratory pathogens; besides, they have non-anti-infective effects, including anti-inflammatory, regulating airway secretion, immune regulation, and other effects. A growing number of studies have shown that the non-anti-infective effects of macrolides have important and potential value in the treatment of pediatric chronic airway diseases; the therapy was described as "long-term, low-dose usage"; unfortunately, there is no guideline or consensus that applies to children. To better carry out the mechanism and clinical research of non-anti-infective effect and promote its rational use in children, the authors summarize the evidence of the usage of long-term, low-dose macrolide antibiotic therapy (LLMAT) in the treatment of chronic airway diseases in children and the progress in recent years. IMPACT: This review summarizes the evidence (mostly in recent 5 years) of the usage of long-term, low-dose macrolide antibiotic therapy in the treatment of chronic airway diseases. The recent studies and guidelines support and enrich the point that long-term, low-dose macrolide antibiotic therapy has potential benefit for children with severe asthma, CF, non-CF bronchiectasis, and BO, which provides clinical references and is of clinical interest. Long-term, low-dose macrolide antibiotic therapy has good safety, and no serious events have been reported; however, potential cardiac side effects and macrolide resistance should be clinically noted.

Ion Channel and Ubiquitin Differential Expression during Erythromycin-Induced Anhidrosis in Foals

Macrolide drugs are the treatment of choice for Rhodococcus equi infections, despite severe side-effects temporary anhidrosis as a. To better understand the molecular biology leading to macrolide induced anhidrosis, we performed skin biopsies and Quantitative Intradermal Terbutaline Sweat Tests (QITSTs) in six healthy pony-cross foals for three different timepoints during erythromycin administration-pre-treatment (baseline), during anhidrosis and post-recovery. RNA sequencing of biopsies followed by differential gene expression analysis compared both pre and post normal sweating timepoints to the erythromycin induced anhidrosis episode. After Bonferroni correction for multiple testing, 132 gene transcripts were significantly differentially expressed during the anhidrotic timepoint. Gene ontology analysis of the full differentially expressed gene set identified over-represented biological functions for ubiquitination and ion-channel function, both biologically relevant to sweat production. These same mechanisms were previously implicated in heritable equine idiopathic anhidrosis and sweat gland function and their involvement in macrolide-induced temporary anhidrosis warrants further investigation.

An empirical comparison of segmented and stochastic linear mixed effects models to estimate rapid disease progression in longitudinal biomarker studies

Longitudinal studies of rapid disease progression often rely on noisy biomarkers; the underlying longitudinal process naturally varies between subjects and within an individual subject over time; the process can have substantial memory in the form of within-subject correlation. Cystic fibrosis lung disease progression is measured by changes in a lung function marker (FEV1), such as a prolonged drop in lung function, clinically termed rapid decline. Choosing a longitudinal model that estimates rapid decline can be challenging, requiring covariate specifications to assess drug effect while balancing choices of covariance functions. Two classes of longitudinal models have recently been proposed: segmented and stochastic linear mixed effects (LMEs) models. With segmented LMEs, random changepoints are used to estimate the timing and degree of rapid decline, treating these points as structural breaks in the underlying longitudinal process. In contrast, stochastic LMEs, such as random walks, are locally linear but utilize continuously changing slopes, viewing bouts of rapid decline as localized, sharp changes. We compare commonly utilized variants of these approaches through an application using the Cystic Fibrosis Foundation Patient Registry. Changepoint modeling had the worst fit and predictive accuracy but certain covariance forms in stochastic LMEs produced problematic variance estimates.

The effectiveness of exercise interventions to increase physical activity in Cystic Fibrosis: A systematic review

Physical activity (PA) and exercise have numerous benefits in Cystic Fibrosis (CF) including improved lung function, exercise capacity and quality of life. Despite these benefits, the effectiveness of interventions to promote PA in this population are still largely unknown. The objective of this review was to synthesise existing research and determine whether exercise interventions are effective in promoting PA in people with CF. Using the PRISMA guidelines, a comprehensive search was conducted. Fifteen studies (463 participants) met the inclusion criteria. Eleven studies demonstrated improvements in PA in both short- and long-term interventions. However, the interventions were variable across the included studies, with a large inconsistency in PA assessment tools used. Aerobic training and activity counselling were the two elements identified in this review which most consistently improved PA. Future research should consider larger sample sizes and the use of accurate instruments to assess and track PA levels longitudinally.

Impact of Anaerobic Antibacterial Spectrum on Cystic Fibrosis Airway Microbiome Diversity and Pulmonary Function

BACKGROUND

The role of anaerobic organisms in the cystic fibrosis (CF) lung microbiome is unclear. Our objectives were to investigate the effect of broad (BS) versus narrow (NS) spectrum antianaerobic antibiotic activity on lung microbiome diversity and pulmonary function, hypothesizing that BS antibiotics would cause greater change in microbiome diversity without a significant improvement in lung function.

METHODS

Pulmonary function tests and respiratory samples were collected prospectively in persons with CF before and after treatment for pulmonary exacerbations. Treatment antibiotics were classified as BS or NS. Gene sequencing data from 16S rRNA were used for diversity analysis and bacterial genera classification. We compared the effects of BS versus NS on diversity indices, lung function and anaerobic/aerobic ratios. Statistical significance was determined by multilevel mixed-effects generalized linear models and mixed-effects regression models.

RESULTS

Twenty patients, 6-20 years of age, experienced 30 exacerbations. BS therapy had a greater effect on beta diversity than NS therapy when comparing time points before antibiotics to after and at recovery. After antibiotics, the NS therapy group had a greater return toward baseline forced expiratory volume at 1 second and forced expiratory flow 25%-75% values than the BS group. The ratio of anaerobic/aerobic organisms showed a predominance of anaerobes in the NS group with aerobes dominating in the BS group.

CONCLUSIONS

BS antianaerobic therapy had a greater and possibly longer lasting effect on the lung microbiome of persons with CF, without achieving the recovery of pulmonary function seen with the NS therapy. Specific antibiotic therapies may affect disease progression by changing the airway microbiome.

Heterogeneity of treatment response in bronchiectasis clinical trials

INTRODUCTION

Recent randomised clinical trials (RCTs) in Bronchiectasis have failed to reach their primary endpoints, suggesting a need to reassess how we measure treatment response. Exacerbations, quality of life (QOL) and lung function are the most common endpoints evaluated in bronchiectasis clinical trials. We aimed to determine the relationship between responses in terms of reduced exacerbations, improved symptoms and lung function in bronchiectasis.

METHODS

We evaluated treatment response in 3 RCTs that evaluated mucoactive therapy (inhaled Mannitol), an oral anti-inflammatory/antibiotic (Azithromycin) and an inhaled antibiotic (Aztreonam). Treatment response was defined by absence of exacerbations during follow-up, an improvement of QOL above the minimum clinically important difference (MCID) and an improvement in FEV₁ of ≥100 mL from baseline.

MEASUREMENTS AND MAIN RESULTS

Cumulatively the three trials included 984 patients. Changes in FEV₁, QOL and exacerbations were heterogeneous in all trials analysed. Improvements in QOL were not correlated to changes in FEV₁ in the azithromycin and aztreonam trials (r=-0.17, p=0.1 and r=0.04, p=0.4) and weakly correlated in the mannitol trial (r=0.22, p<0.0001). An important placebo effect was observed in all trials, especially regarding improvements in QOL. Clinical meaningful lung function improvements were rare across all trials evaluated, suggesting that FEV₁ is not a responsive measure in bronchiectasis.

CONCLUSIONS

Improvements in lung function, symptoms and exacerbation frequency are dissociated in bronchiectasis. FEV₁ is poorly responsive and poorly correlated with other key outcome measures. Clinical parameters are poorly predictive of treatment response suggesting the need to develop biomarkers to identify responders.

Forced Oscillation Technique for Monitoring the Respiratory Status of Children with Cystic Fibrosis: A Systematic Review

Spirometry is considered the gold standard method for monitoring lung function of patients with cystic fibrosis (CF) but it requires patients’ cooperation and therefore it is not useful for the majority of preschool-aged children. Oscillometry is an alternative modality for lung function monitoring that requires minimal cooperation and can be applied in children as young as 3 years of age. Furthermore, it generates lesser aerosol compared to spirometry, an issue that is of considerable importance in the COVID-19 era. The aim of this review was to present the existing clinical data regarding the application of oscillometry in children and adolescents with CF. The method seems to have acceptable feasibility and repeatability. However, there is conflicting data regarding the correlation of oscillometry values with the clinical symptoms of CF patients either in clinically stable or in exacerbation periods. Furthermore, it is not clear to what extent oscillometry measurements correlate with the spirometry indices. Based on current evidence, spirometry cannot be substituted by oscillometry in the monitoring of the respiratory status of children and adolescents with CF.

The Gut-Lung Axis in Cystic Fibrosis

Cystic fibrosis (CF) is a heritable, multiorgan disease that impacts all tissues that normally express cystic fibrosis transmembrane conductance regulator (CFTR) protein. While the importance of the airway microbiota has long been recognized, the intestinal microbiota has only recently been recognized as an important player in both intestinal and lung health outcomes for persons with CF (pwCF). Here, we summarize current literature related to the gut-lung axis in CF, with a particular focus on three key ideas: (i) mechanisms through which microbes influence the gut-lung axis, (ii) drivers of microbiota alterations, and (iii) the potential for intestinal microbiota remediation.

New Insights in Microbial Species Predicting Lung Function Decline in CF: Lessons from the MucoFong Project

Several predictive models have been proposed to understand the microbial risk factors associated with cystic fibrosis (CF) progression. Very few have integrated fungal airways colonisation, which is increasingly recognized as a key player regarding CF progression. To assess the association between the percent predicted forced expiratory volume in 1 s (ppFEV1) change and the fungi or bacteria identified in the sputum, 299 CF patients from the “MucoFong” project were included and followed-up with over two years. The relationship between the microorganisms identified in the sputum and ppFEV1 course of patients was longitudinally analysed. An adjusted linear mixed model analysis was performed to evaluate the effect of a transient or chronic bacterial and/or fungal colonisation at inclusion on the ppFEV1 change over a two-year period. Pseudomonas aeruginosa, Achromobacter xylosoxidans, Stenotrophomonas maltophilia, and Candida albicans were associated with a significant ppFEV1 decrease. No significant association was found with other fungal colonisations. In addition, the ppFEV1 outcome in our model was 11.26% lower in patients presenting with a transient colonisation with non-pneumoniae Streptococcus species compared to other patients. These results confirm recently published data and provide new insights into bacterial and fungal colonisation as key factors for the assessment of lung function decline in CF patients.

Patterns of Health Insurance Coverage and Lung Disease Progression in Adolescents and Young Adults with Cystic Fibrosis

Rationale: Health insurance coverage has been implicated as a socioeconomic factor affecting clinical outcomes in patients with cystic fibrosis (CF), but evidence for this is mixed and varies by age.Objectives: Focusing on adolescents and young adults with CF, we examined how multiyear patterns of health insurance coverage were associated with lung function decline and related outcomes.Methods: We used data from the 2000 to 2015 CF Foundation Patient Registry to classify patients in three cohorts (ages 12-17 yr, adolescents; 18-23 yr, transitioning to adulthood; and 24-29 yr, young adults) according to health insurance coverage, as follows: continuous private, continuous public, intermittent public, and coverage gaps. The primary outcome was the percentage predicted forced expiratory volume in 1 second (FEV₁pp), which was modeled using mixed-effects regression. Additional outcomes included outpatient visits, hospital days for pulmonary exacerbation treatment, bacterial colonization, and body mass index. Outcomes were assessed over a 6-year period (e.g., ages 12-17 yr), whereas exposures were assessed over the prior 6 years (e.g., ages 6-11 yr).Results: The three cohorts included 3,365, 2,800, and 1,807 patients, respectively. The highest rate of FEV₁pp decline was found in the middle cohort, with the annual decline being steeper among patients with continuous public (-3.1/yr; 95% confidence interval [CI], -3.3 to -2.8) or intermittent public (-2.4/yr; 95% CI, -2.6 to -2.2) coverage compared with patients with continuous private coverage (-2.1/yr; 95% CI, -2.2 to -2.0). These differences were not explained by differences in outpatient care utilization.Conclusions: During the transition to adulthood, use of public insurance was associated with accelerated lung function decline among patients with CF. The role of insurance as a causal factor in this decline or proxy for other socioeconomic characteristics should be explored in further studies.

Unsupervised phenotypic clustering for determining clinical status in children with cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) is a multisystem disease in which the assessment of disease severity based on lung function alone may not be appropriate. The aim of the study was to develop a comprehensive machine-learning algorithm to assess clinical status independent of lung function in children.

METHODS

A comprehensive prospectively collected clinical database (Toronto, Canada) was used to apply unsupervised cluster analysis. The defined clusters were then compared by current and future lung function, risk of future hospitalisation, and risk of future pulmonary exacerbation treated with oral antibiotics. A k-nearest-neighbours (KNN) algorithm was used to prospectively assign clusters. The methods were validated in a paediatric clinical CF dataset from Great Ormond Street Hospital (GOSH).

RESULTS

The optimal cluster model identified four (A-D) phenotypic clusters based on 12 200 encounters from 530 individuals. Two clusters (A and B) consistent with mild disease were identified with high forced expiratory volume in 1 s (FEV₁), and low risk of both hospitalisation and pulmonary exacerbation treated with oral antibiotics. Two clusters (C and D) consistent with severe disease were also identified with low FEV₁. Cluster D had the shortest time to both hospitalisation and pulmonary exacerbation treated with oral antibiotics. The outcomes were consistent in 3124 encounters from 171 children at GOSH. The KNN cluster allocation error rate was low, at 2.5% (Toronto) and 3.5% (GOSH).

CONCLUSION

Machine learning derived phenotypic clusters can predict disease severity independent of lung function and could be used in conjunction with functional measures to predict future disease trajectories in CF patients.

Evaluating the Impact of Stopping Chronic Therapies after Modulator Drug Therapy in Cystic Fibrosis: The SIMPLIFY Clinical Trial Study Design

The care for individuals with cystic fibrosis (CF) with at least one F508del mutation will greatly change as a result of the unparalleled clinical benefits observed with the new triple-combination CFTR (CF transmembrane regulator)-modulator therapy elexacaftor/tezacaftor/ivacaftor (ETI). Incorporating ETI into the standard of care creates new motivation and opportunity to consider reductions in overall treatment burden and evaluate whether other chronic medications can now be safely discontinued without loss of clinical benefit. SIMPLIFY is a master protocol poised to test the impact of discontinuing versus continuing two commonly used chronic therapies in people with CF who are at least 12 years of age or older and stable on ETI therapy. The protocol is composed of two concurrent randomized controlled trials designed to evaluate the independent short-term effects of discontinuing hypertonic saline or dornase alfa, enabling individuals on both therapies to participate in one or both trials. The primary objective for each trial is to determine whether discontinuing treatment is noninferior to continuing treatment after establishment of ETI, as measured by the 6-week absolute change in the percent-predicted forced expiratory volume in 1 second. Developing this study required a balance between ideal study-design principles and feasibility. SIMPLIFY will be the largest multicenter, randomized, controlled medication-withdrawal study in CF. This study is uniquely positioned to provide timely evidence on whether the daily treatment burden can be reduced among individuals on CFTR-modulator therapy. Clinical trial registered with www.clinicaltrials.gov (NCT04378153).

The measurement properties of tests and tools used in cystic fibrosis studies: a systematic review

There is no consensus on how best to measure responses to interventions among children and adults with cystic fibrosis (CF). We have systematically reviewed and summarised the characteristics and measurement properties of tests and tools that have been used to capture outcomes in studies among people with CF, including their reliability, validity and responsiveness. This review is intended to guide researchers when selecting tests or tools for measuring treatment effects in CF trials. A consensus set of these tests and tools could improve consistency in how outcomes are captured and thereby facilitate comparisons and synthesis of evidence across studies.

An Animated Functional Data Analysis Interface to Cluster Rapid Lung Function Decline and Enhance Center-Level Care in Cystic Fibrosis

Identifying disease progression through enhanced decision support tools is key to chronic management in cystic fibrosis at both the patient and care center level. Rapid decline in lung function relative to patient level and center norms is an important predictor of outcomes. Our objectives were to construct and utilize center-level classification of rapid decliners to develop an animated dashboard for comparisons within patients over time, multiple patients within centers, or between centers. A functional data analysis technique known as functional principal components analysis was applied to lung function trajectories from 18,387 patients across 247 accredited centers followed through the United States Cystic Fibrosis Foundation Patient Registry, in order to cluster patients into rapid decline phenotypes. Smaller centers (<30 patients) had older patients with lower baseline lung function and less severe rates of decline and had maximal decline later, compared to medium (30-150 patients) or large (>150 patients) centers. Small centers also had the lowest prevalence of early rapid decliners (17.7%, versus 24% and 25.7% for medium and large centers, resp.). The animated functional data analysis dashboard illustrated clustering and center-specific summaries of the rapid decline phenotypes. Clinical scenarios and utility of the center-level functional principal components analysis (FPCA) approach are considered and discussed.

Reliability of impulse oscillometry parameters in healthy children and in children with cystic fibrosis

INTRODUCTION & AIMS

Impulse oscillometry system (IOS) is an instrument developed to evaluate the mechanical lung properties. It has been reported that to analyse the exam in a proper way it is necessary to carry out more than one measure. However, studies addressing the standardisation are still scarce. The objective was to determine within trial reliability of three measures in IOS parameters in healthy children and children with cystic fibrosis (CF).

METHOD

Weight, height, body mass index, forced spirometric and the oscillometric parameters (resistance, respiratory impedance, respiratory reactance and resonance frequency) data were collected, in a way that all participants performed three IOS measures. To evaluate, the reproducibility was used the intraclass correlation coefficient [two-way mixed model, absolute agreement definition, ICC]. The response stability was appraised using the standard error of measurements (SEM) in three repetitions of the IOS in the healthy children group (HCG) and in the cystic fibrosis group (CFG).

RESULTS

About 95 subjects participated, in each group with a mean age of 10.89 ± 2.21 years old in the HCG and 9.73 ± 2.43 years old in the CFG, having been 41 and 43 boys and 54 and 52 girls, in the respectively group. In both groups, all IOS parameters evaluated in the three measures presented an ICC of 0.9, which is a high reproducibility.

CONCLUSION

The IOS parameters are reproducible for healthy children and CF children in three measures. However, according to the population studied, the performance of only one measure is sufficient to assess respiratory mechanics, whereas the SEM were low, except for Fres, in both groups.

Cystic Fibrosis: Recent Insights into Inhaled Antibiotic Treatment and Future Perspectives

Although new inhaled antibiotics have profoundly improved respiratory diseases in cystic fibrosis (CF) patients, lung infections are still the leading cause of death. Inhaled antibiotics, i.e., colistin, tobramycin, aztreonam lysine and levofloxacin, are used as maintenance treatment for CF patients after the development of chronic Pseudomonas aeruginosa (P. aeruginosa) infection. Their use offers advantages over systemic therapy since a relatively high concentration of the drug is delivered directly to the lung, thus, enhancing the pharmacokinetic/pharmacodynamic parameters and decreasing toxicity. Notably, alternating treatment with inhaled antibiotics represents an important strategy for improving patient outcomes. The prevalence of CF patients receiving continuous inhaled antibiotic regimens with different combinations of the anti-P. aeruginosa antibiotic class has been increasing over time. Moreover, these antimicrobial agents are also used for preventing acute pulmonary exacerbations in CF. In this review, the efficacy and safety of the currently available inhaled antibiotics for lung infection treatment in CF patients are discussed, with a particular focus on strategies for eradicating P. aeruginosa and other pathogens. Moreover, the effects of long-term inhaled antibiotic therapy for chronic P. aeruginosa infection and for the prevention of pulmonary exacerbations is reviewed. Finally, how the mucus environment and microbial community richness can influence the efficacy of aerosolized antimicrobial agents is discussed.