An insight into vitamin E and lipid nutrition of the plains-wanderer Pedionomus torquatus.

Vitamin E, as α-tocopherol, is an essential antioxidant protecting the body from free radicals. The vitamin E requirement of managed wildlife species is known to be greater than their wild counterparts, predominantly due to higher dietary lipid content and potentially stressful environments. The plains-wanderer (Pedionomus torquatus, Family Pedionomidae [monotypical]) is a critically endangered, superficially quail-like bird that is the focus of an ongoing captive breeding programme in Australia. It is estimated that plains-wanderers have a high vitamin E requirement (compared with domestic poultry species) to offset a high lipid diet and their naturally flighty temperament. This study therefore aims to gain a greater understanding of the nutritional status and vitamin E requirements of plains-wanderers in managed environments. Total lipid and α-tocopherol intake were quantified for 26 zoo-managed plains-wanderers over a series of diet intake trials in addition to measurement of plasma α-tocopherol and cholesterol concentrations. Plains-wanderers that consumed higher portions of dietary fat had significantly lower circulating α-tocopherol concentrations than birds that consumed lower total dietary fat (p < .001). Additionally, plasma cholesterol concentrations of managed plains-wanderers were found to be significantly greater than all other bird species reviewed, irrespective of Family or feeding type. We also present the first published data quantifying the nutritional makeup of stomach contents of a wild plains-wanderer for use as a potential guide for diet formulation. This study forms a vital foundational insight into the nutritional management of plains-wanderers, but further research is required to understand their dietary habits and cholesterol metabolism.

Cardiopulmonary Exercise Testing Provides Prognostic Information in Advanced Cystic Fibrosis Lung Disease.

Rationale: Cardiopulmonary exercise testing (CPET) provides prognostic information in cystic fibrosis (CF); however, its prognostic value for patients with advanced CF lung disease is unknown. Objectives: To determine the prognostic value of CPET on the risk of death or lung transplant (LTX) within 2 years. Methods: We retrospectively collected data from 20 CF centers in Asia, Australia, Europe, and North America on patients with a forced expiratory volume in 1 second (FEV1) ⩽ 40% predicted who performed a cycle ergometer CPET between January 2008 and December 2017. Time to death/LTX was analyzed using mixed Cox proportional hazards regression. Conditional inference trees were modeled to identify subgroups with increased risk of death/LTX. Results: In total, 174 patients (FEV1, 30.9% ± 5.8% predicted) were included. Forty-four patients (25.5%) died or underwent LTX. Cox regression analysis adjusted for age, sex, and FEV1 revealed percentage predicted peak oxygen uptake ([Formula: see text]o2peak) and peak work rate (Wpeak) as significant predictors of death/LTX: adjusted hazard ratios per each additional 10% predicted were 0.60 (95% confidence interval, 0.43-0.90; P = 0.008) and 0.60 (0.48-0.82; P < 0.001). Tree-structured regression models, including a set of 11 prognostic factors for survival, identified Wpeak to be most strongly associated with 2-year risk of death/LTX. Probability of death/LTX was 45.2% for those with a Wpeak ⩽ 49.2% predicted versus 10.9% for those with a Wpeak > 49.2% predicted (P < 0.001). Conclusions: CPET provides prognostic information in advanced CF lung disease, and Wpeak appears to be a promising marker for LTX referral and candidate selection.

In Situ Provisioning Wildlife with Food, Water, or Shelter after Bushfires: Using a One Welfare Framework to Guide Responses.

Australia's 2019-2020 bushfires had a devastating impact on animals, humans, and ecosystems. They also demonstrated the lack of evidence or guidance for wildlife provisioning in response to severe fire events when volunteers and wildlife organisations rose to respond. In addition, the unprecedented scale and intensity of the fires and an absence of institutional support for wildlife provisioning meant that well-intentioned interventions were largely uncoordinated and lacked clear short-term, mid-term, and long-term objectives. Fundamentally, a lack of consensus was revealed on whether any such interventions are advisable. Given the strong evidence indicating that future bushfire seasons will become longer and more intense in Australia and elsewhere, the welfare and survival of millions of wild animals are at risk every year. Understanding the impacts of supplementary resource interventions and contributing to the development of best practice information is crucial to inform the response to the next major fire event. Here, we contextualize the arguments for and against provisioning within a 'One Welfare' framework that recognizes that animal welfare, biodiversity, and the environment are intertwined with human welfare and community resilience. We propose that the One Welfare approach can facilitate appropriate consideration of the extant scientific and lay literature; local legislation; views of stakeholders; emerging data; and modelling from historic fire events. As a further step, we see merit in engaging with wildlife provisioners and the broader conservation community to build an evidence base for future wildlife provisioning activities. From an informed position, we can encourage beneficial interventions and reduce the risk of negative outcomes. Finally, we propose controlled experiments (e.g., using hazard reduction burns), ongoing data collection using emergent technology, and longitudinal analysis to address shifting research priorities as the climate changes. We conclude that the ordered collection of the necessary evidence relevant to each of the three stakeholder groups in the One Welfare framework has the greatest potential to support an informed policy platform on wildlife provisioning across Australia that is feasible, legal, and sustainable.

Longitudinal Assessment of Curaçao Criteria in Children with Hereditary Hemorrhagic Telangiectasia.

OBJECTIVE: To assess the utility of the Curaçao criteria by age over time in children with hereditary hemorrhagic telangiectasia (HHT). STUDY DESIGN: This was a single-center, retrospective analysis of patients attending the HHT clinic at the Hospital for Sick Children (Toronto, Canada) between 2000 and 2019. The evaluation of the Curaçao criteria was completed during initial and follow-up visits. Screening for pulmonary and brain arteriovenous malformations was completed at 5 yearly intervals. RESULTS: A total of 116 patients with genetic confirmation of HHT were included in the analysis. At initial screening at a median (IQR) age of 8.4 (2.8, 12.9) years, 41% met criteria for a definite clinical diagnosis (≥3 criteria). In children <6 years at presentation, only 23% fulfilled at least 3 criteria initially. In longitudinal follow-up, 63% reached a definite clinical diagnosis, with a median (IQR) follow-up duration of 5.2 (3.2, 7.9) years (P = .005). Specifically, more patients met the epistaxis and telangiectasia criteria at last visit compared with initial (79% vs 60%; P = .006; 47% vs 30%; P = .02) but not for the arteriovenous malformation criterion (59% vs 57%; P = .65). CONCLUSIONS: In the pediatric population, most patients do not meet definite clinical criteria of HHT at initial presentation. Although the number of diagnostic criteria met increased over time, mainly due to new onset of epistaxis and telangiectasia, accuracy remained low during follow-up visits. Relying solely on clinical criteria may lead to underdiagnosis of HHT in children.

Factors associated with lung function response with oral antibiotic treatment of pulmonary exacerbations in cystic fibrosis.

Pulmonary exacerbations treated with oral antibiotics (oPEx) have a significant effect on lung function decline in people with cystic fibrosis (CF). However, factors associated with lung function response with oPExs are not well defined. We performed a retrospective cohort study of pediatric and adult patients with CF followed in the Toronto CF Database. Lung function response was measured both as the change in forced expiratory volume in 1 second (FEV1) from Day 0 of antibiotic therapy to end of treatment as well as from baseline to end of treatment. Drop from baseline to Day 0 FEV1 was strongly associated with lung function response (p<0.001). Greater FEV1 improvements were associated with longer antibiotic treatment durations. Older, female patients had less improvements in FEV1 at end of treatment compared to younger, male patients.

Treatment response to pulmonary exacerbation in primary ciliary dyskinesia.

INTRODUCTION: Pulmonary exacerbation (Pex) are common in pediatric primary ciliary dyskinesia (PCD), however changes in forced expiratory volume in 1 s precent predicted (FEV1pp) during Pex are not well described. AIM: To assess the evolution of FEV1pp during Pex and to define factors associated with failure to return to baseline lung function. METHOD: This was a retrospective study of patients with PCD between 2010 and 2022. Pex were defined as the presence of increased respiratory symptoms treated with intravenous (IV) antibiotics. The main outcomes were the changes in FEV1 during therapy and the proportion of patients (responders) achieving ≥90% of baseline FEV1pp values at the end of admission. RESULTS: The study included 52 Pex events in 28 children with PCD. The rate of responders was 32/41 (78%) at the end of admission. Nonresponse was associated with lower median body mass index (BMI) Z-score (-2.4 vs. -0.4, p < .01) and with a history of IV treated Pex in the previous year (p = .06). For the 22 Pex with available FEV1pp measurements at mid admission, the median relative and absolute improvement from admission to Day 7 was 9.1% and 6.2%, respectively (p- .001), and from Days 7 to 14 was 4.4% and 2.8%, respectively (p = .08). CONCLUSION: In children with PCD treated with IV antibiotics, the majority of lung function recovery happens during the first week of IV therapy. Lower BMI was associated with nonresponse to therapy.

Efficacy of Antibiotic Eradication Therapy of Early Pseudomonas aeruginosa Infection in Children with Primary Ciliary Dyskinesia.

Rationale: Chronic infection with Pseudomonas aeruginosa (PsA) negatively impacts lung disease in patients with primary ciliary dyskinesia (PCD). There is currently limited evidence regarding the efficacy of PsA antibiotic eradication therapy (AET) in children with PCD. Objectives: To assess the effectiveness of AET of early PsA infection in children with PCD. Methods: This retrospective study included pediatric patients with a confirmed PCD diagnosis according to the American Thoracic Society guidelines at the Hospital for Sick Children between 2010 and 2022. Children with newly acquired PsA infection underwent AET using a stepwise protocol. The protocol included the following steps: step 1, 28 days of tobramycin inhalation solution (TIS); step 2, repeat TIS if culture positive after step 1; and step 3, 14 days of intravenous antibiotics followed by 28 days of TIS if culture positive after step 2. Step 3 was also used for patients who presented with pulmonary exacerbation symptoms. The main outcome was a PsA-negative culture result based on the microbiological results of the first culture after completion of each step of treatment. Results: During the study period, 31 children had a new PsA infection and underwent AET. Of the 27 children who had been asymptomatic at the time of the PsA infection, negative PsA culture results were achieved in 20 (74%) of 27, 1 (14%) of 7, and 5 (83%) of 6 after steps 1, 2, and 3 of AET, respectively. All four symptomatic patients who initially were treated with step 3 had successful clearance of PsA. The overall cumulative success rate of the protocol for negative culture results after AET was 97% (30 of 31). For patients in whom AET was successful, the probability of staying PsA free for at least 1 year was 70%. Conclusions: AET for early PsA infection is highly effective in PCD, with sustained efficacy in most individuals. These data suggest that AET should be considered in all children with PCD who have early PsA infection.

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

INTRODUCTION: While antibiotic eradication therapy (AET) of early Pseudomonas aeruginosa infection is considered standard of care, its long-term effect on the subsequent course of cystic fibrosis (CF) lung disease remains unclear. METHODS: CF patients who were P. aeruginosa-free for at least a year and had a minimum of 10 years of pulmonary function measurements were included. Subjects were categorized as Never if they never had P. aeruginosa isolated from a respiratory tract sample. Subjects changed to the Eradicated group if they had a P. aeruginosa infection, were treated with AET, and subsequently cleared their infection. Subjects changed to the Chronic group if AET did not clear their P. aeruginosa infection. The primary outcome was absolute FEV1 decline over time, with age as the time variable. Mixed-effects linear regression models were used to account for the repeated lung function measurements over time within each patient. RESULTS: 205 CF subjects (48% female) were included; the median (IQR) age at first infection was 9.6 (5.6, 14.6) years. The median (IQR) follow-up was 10.2 (5.7, 14.7) years for the Eradicated group, 8.8 (4.5, 14.9) years for the Chronic group and 2.8 (1.0, 5.7) years for the Never group was among those patients that had at least one P. aeruginosa infection over the study period, annual lung function decline of FEV1 was significantly less (-1.11% predicted/year; 95% CI: -1.18, -1.04) in the Eradication group compared to the Chronic group (-1.57%; -1.64, -1.50) (p<0.001). CONCLUSIONS: AET against P. aeruginosa improves lung function trajectory in CF patients.

Comparative analysis of respiratory symptom scores to detect acute respiratory events in children with cystic fibrosis.

BACKGROUND: Patient-reported outcomes (PROs) are important outcome measures in research and clinical practice. This study describes the longitudinal variability the Cystic Fibrosis Questionnaire-Revised (CFQ-R) Respiratory score and the Chronic Respiratory Infection Symptom Score (CRISS), as well as their ability to identify acute respiratory events in children with CF. METHODS: In this prospective observational study, the parent-proxy (6 -13 years) and self-reported (6-18 years) CFQ-R Respiratory score and CRISS (6-18 years) were measured every 3 months over 2 years. The lung clearance index (LCI) and FEV1 were also measured. We compared the diagnostic accuracy of the PROs in distinguishing acute respiratory events and clinically stable visits, using the minimal important difference of each PRO as the threshold. RESULTS: A total of 98 children with CF were included. On average, the symptom scores did not change between clinically stable visits. The positive predictive value (PPV) and negative predictive value (NPV) of a ≥8.5-point worsening in the parent-proxy CFQ-R score to identify acute respiratory events (n=119) (PPV 70.2% and NPV 87.0%) were higher than for the self-reported CFQ-R score (PPV 58.9% and NPV 72.2%). The PPV and NPV of an ≥11-point change in the CRISS for acute respiratory events (n=137) was 56.5% and 79.6%, respectively. The PPV and NPV of all PROs were increased when combined with the LCI and/or FEV1pp. CONCLUSION: Symptoms scores differ in their ability to identify acute respiratory events in children with CF; PPV and NPV of all PROs were improved when combined with lung function outcomes.

Characterising the Gut Microbiomes in Wild and Captive Short-Beaked Echidnas Reveals Diet-Associated Changes.

The gut microbiome plays a vital role in health and wellbeing of animals, and an increasing number of studies are investigating microbiome changes in wild and managed populations to improve conservation and welfare. The short-beaked echidna (Tachyglossus aculeatus) is an iconic Australian species, the most widespread native mammal, and commonly held in zoos. Echidnas are cryptic animals, and much is still unknown about many aspects of their biology. Furthermore, some wild echidna populations are under threat, while echidnas held in captivity can have severe gastric health problems. Here, we used citizen science and zoos to collect echidna scats from across Australia to perform the largest gut microbiome study on any native Australian animal. Using 16S rRNA gene metabarcoding of scat samples, we characterised and compared the gut microbiomes of echidnas in wild (n = 159) and managed (n = 44) populations, which were fed four different diets. Wild echidna samples were highly variable, yet commonly dominated by soil and plant-fermenting bacteria, while echidnas in captivity were dominated by gut commensals and plant-fermenting bacteria, suggesting plant matter may play a significant role in echidna diet. This work demonstrates significant differences between zoo held and wild echidnas, as well as managed animals on different diets, revealing that diet is important in shaping the gut microbiomes in echidnas. This first analysis of echidna gut microbiome highlights extensive microbial diversity in wild echidnas and changes in microbiome composition in managed populations. This is a first step towards using microbiome analysis to better understand diet, gastrointestinal biology, and improve management in these iconic animals.

The effect of antibiotic changes during treatment of cystic fibrosis pulmonary exacerbations.

BACKGROUND: Antibiotics are often changed during treatment of pulmonary exacerbations (PEx) in people with cystic fibrosis (CF) who have a poor clinical response. We aimed to characterize the reasons CF providers change antibiotics and examined the effects of antibiotic changes on lung function recovery. METHODS: This was a retrospective cohort study using the Toronto CF Database from 2009 to 2015 of adults and children with CF PEx treated with intravenous antibiotics. The co-primary outcome measure was absolute and relative change in forced expiratory lung volume in 1 s (FEV1) at end of treatment and follow-up. Secondary outcome assessed the proportion of patients returning to > 90% or > 100% previous baseline FEV1. RESULTS: A total of 399 PEx were included of which 105 had antibiotic changes. Reasons for antibiotic changes included change in antibiotic route prior to discharge (26%), drug reactions (20%), poor FEV1 response (25%), targeting additional microbes (16%) and lack of symptom improvement (13%). In our multivariable analysis, among non-responders (< 90% FEV1 recovery to baseline or lack of symptom improvement at the interim time point), a change in antibiotics was not associated with any significant difference in absolute or relative FEV1 at end of treatment or at follow-up. Antibiotic change in non-responders was not associated with improved return to 90% or 100% baseline FEV1 at end of treatment or follow-up. CONCLUSIONS: Changing antibiotics during CF PEx treatment in those with poor clinical response was not associated with any improved FEV1 response or return to baseline lung function.

Genetic evidence supports the development of SLC26A9 targeting therapies for the treatment of lung disease.

Over 400 variants in the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) are CF-causing. CFTR modulators target variants to improve lung function, but marked variability in response exists and current therapies do not address all CF-causing variants highlighting unmet needs. Alternative epithelial ion channel/transporters such as SLC26A9 could compensate for CFTR dysfunction, providing therapeutic targets that may benefit all individuals with CF. We investigate the relationship between rs7512462, a marker of SLC26A9 activity, and lung function pre- and post-treatment with CFTR modulators in Canadian and US CF cohorts, in the general population, and in those with chronic obstructive pulmonary disease (COPD). Rs7512462 CC genotype is associated with greater lung function in CF individuals with minimal function variants (for which there are currently no approved therapies; p = 0.008); and for gating (p = 0.033) and p.Phe508del/ p.Phe508del (p = 0.006) genotypes upon treatment with CFTR modulators. In parallel, human nasal epithelia with CC and p.Phe508del/p.Phe508del after Ussing chamber analysis of a combination of approved and experimental modulator treatments show greater CFTR function (p = 0.0022). Beyond CF, rs7512462 is associated with peak expiratory flow in a meta-analysis of the UK Biobank and Spirometa Consortium (p = 2.74 × 10-44) and provides p = 0.0891 in an analysis of COPD case-control status in the UK Biobank defined by spirometry. These findings support SLC26A9 as a therapeutic target to improve lung function for all people with CF and in individuals with other obstructive lung diseases.

Interleukin-1 beta is a potential mediator of airway nitric oxide deficiency in cystic fibrosis.

Airway nitric oxide (NO) deficiency is a hallmark of cystic fibrosis (CF), but the reasons for the reduced NO production in CF airways are unclear. Interleukin (IL)-1 pathway activation plays a role in early CF lung disease and is also involved in the regulation of NO synthase activity. Treatment of CF patients with the CFTR-targeting drug ivacaftor, among other beneficial effects, results in an increase in airway NO levels. In this longitudinal observational trial, we show that ivacaftor therapy leads to a significant reduction in sputum IL-1ß concentration but not in other IL-1- or Th17-associated cytokines. IL-1ß concentrations were closely linked to improvement in pulmonary function, measures of NO metabolism in sputum and exhaled NO. These data therefore suggest a potential interaction between transepithelial chloride conductance, IL-1ß and airway NO production.

Aquagenic wrinkling of the palms in cystic fibrosis patients treated with ivacaftor.

Aquagenic wrinkling of palms (AWP) in cystic fibrosis (CF) patients and common CFTR mutations is recognized as a frequent symptom of the disease. The long-term effect of CFTR targeting therapy on AWP has not been studied. AWP was monitored in 16 CF patients (8 children and 8 adults) before and for 6 months after initiation of ivacaftor therapy. Thirteen (81.3%) patients had at least mild and 8/16 (50%) moderate-to-severe AWP at baseline. AWP improved with ivacaftor therapy. This observation suggests that AWP is also common in individuals with CF and relatively rare mutations and is directly related to CFTR function.

Bronchodilator responsiveness in cystic fibrosis children treated for pulmonary exacerbations.

BACKGROUND: Cystic fibrosis (CF) pulmonary exacerbations (PEx) are associated with a significant drop in pulmonary function. The clinical value of measuring bronchodilator (BD) responsiveness during treatment for PEx to monitor or predict recovery of lung function is unclear. METHODS: A retrospective analysis of spirometry with BD response testing obtained during hospital admissions for PEx in pediatric CF patients. Repeated events were included for patients with BD testing during multiple admissions. RESULTS: Two hundred forty-nine spirometries with BD testing in 102 patients were completed around Day 7 (Days 4-10) of hospital admission for treatment of CF PEx. Median (IQR) forced expiratory volume in 1 s (FEV1 ) was 70.6% predicted (58.1, 84.6) before the PEx event (best FEV1 in 6 months before admission), 54.4% (41.5, 66.9) at admission, 62.3% (48.4, 74.7) around Day 7 of admission and 67.1% predicted (53.8, 78.2) at the end of treatment. BD response around Day 7 correlated poorly with FEV1 before PEx (r = -.16, p = .02) and did not correlate with recovery to baseline FEV1 at end of treatment (r = .08, p = .22). Only 23/249 (9%) individual tests had a BD response in FEV1 of ≥12% and 200 ml. BD response was not related to age or severity of lung disease and led to an immediate change in clinical management in only four cases. CONCLUSIONS: Significant BD response in CF patients treated for PEx is rare, shows poor correlation with baseline pulmonary function and does not correlate with the recovery of FEV1 with treatment. These data suggest that routine testing for BD response is not indicated during PEx.

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

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

Lung Clearance Index to Track Acute Respiratory Events in School-Age Children with Cystic Fibrosis.

Rationale: The lung clearance index (LCI) is responsive to acute respiratory events in preschool children with cystic fibrosis (CF), but its utility to identify and manage these events in school-age children with CF is not well defined.Objectives: To describe changes in LCI with acute respiratory events in school-age children with CF.Methods: In a multisite prospective observational study, the LCI and FEV1 were measured quarterly and during acute respiratory events. Linear regression was used to compare relative changes in LCI and FEV1% predicted at acute respiratory events. Logistic regression was used to compare the odds of a significant worsening in LCI and FEV1% predicted at acute respiratory events. Generalized estimating equation models were used to account for repeated events in the same subject.Measurements and Main Results: A total of 98 children with CF were followed for 2 years. There were 265 acute respiratory events. Relative to a stable baseline measure, LCI (+8.9%; 95% confidence interval, 6.5 to 11.3) and FEV1% predicted (-6.6%; 95% confidence interval, -8.3 to -5.0) worsened with acute respiratory events. A greater proportion of events had a worsening in LCI compared with a decline in FEV1% predicted (41.7% vs. 30.0%; P = 0.012); 53.9% of events were associated with worsening in LCI or FEV1. Neither LCI nor FEV1 recovered to baseline values at the next follow-up visit.Conclusions: In school-age children with CF, the LCI is a sensitive measure to assess lung function worsening with acute respiratory events and incomplete recovery at follow-up. In combination, the LCI and FEV1 capture a higher proportion of events with functional impairment.

CFTR-function and ventilation inhomogeneity in individuals with cystic fibrosis.

BACKGROUND: Increased (abnormal) ventilation inhomogeneity in individuals with mild Cystic Fibrosis (CF) lung disease may become a treatable trait for small-molecule therapeutics improving Cystic Fibrosis Transmembrane Regulator (CFTR) function. The relationship between CFTR function and ventilation inhomogeneity is unknown. We aimed to identify and quantify increased ventilation inhomogeneity in relation to CFTR function. METHODS: This was an international, multi-center, cross-sectional study. We collated data from individuals aged 3-25 years with minimal (CFTR-MF) or residual (CFTR-RF) function of a variety of CFTR genotypes and FEV1 ≥ 70% predicted. We measured lung function using nitrogen multiple-breath washout and spirometry. We compared lung clearance index (LCI) and FEV1 between individuals with CFTR-MF vs CFTR-RF using a mixed effects multi-variable linear regression model to account for study differences and a logistic model based on propensity-score matching to adjust for possible confounding. RESULTS: We included 141 with CFTR-MF and 35 with CFTR-RF. LCI (> 1.96 z-score) was elevated in 71.6% individuals with CFTR-MF and in 40.0% with CFTR-RF. FEV1 (< -1.96 z-score) was reduced in 11.3% individuals with CFTR-MF and in 5.7% with CFTR-RF. The mean difference (95% CI) of LCI and FEV1 between CFTR-MF and CFTR-RF was 3.71 (1.63 to 5.79) and -0.40 (-0.83 to 0.02) z-score. The LCI differences were similar after adjustment for confounders and in individuals with normal FEV1. CONCLUSION: Increased ventilation inhomogeneity is associated with less CFTR function. In individuals with mild CF lung disease, LCI can identify and quantify increased ventilation inhomogeneity, a candidate treatable trait.