Survival estimates in European cystic fibrosis patients and the impact of socioeconomic factors: a retrospective registry cohort study

Standards for the care of people with cystic fibrosis (CF); Planning for a longer life

This is the final of four papers updating standards for the care of people with CF. That this paper "Planning a longer life" was considered necessary, highlights how much CF care has progressed over the past decade. Several factors underpin this progress, notably increased numbers of people with CF with access to CFTR modulator therapy. As the landscape for CF changes, so do the hopes and aspirations of people with CF and their families. This paper reflects the need to consider people with CF not as a "problem" to be solved, but as a success, a potential and a voice to be heard. People with CF and the wider CF community have driven this approach, reflecting many of the topics in this paper. This exercise involved wide stakeholder engagement. People with CF are keen to contribute to research priorities and be involved in all stages of research. People with CF want healthcare professionals to respect them as individuals and consider the impact of our actions on the world around us. Navigating life presents challenges to all, but for people with CF these challenges are heightened and complex. In this paper we highlight the concerns and life moments that impact people with CF, and events that the CF team should aim to support, including the challenges around having a family. People with CF and their care teams must embrace the updated standards outlined in these four papers to enjoy the full potential for a healthier life.

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.

Global disparities in cystic fibrosis outcomes prior to CFTR modulators: A CF registries cohort study in South Africa and Canada

BACKGROUND

Outcomes of cystic fibrosis (CF) differ between low-middle income and high-income countries, but comparative data are lacking. We compared South African (SA) and Canadian CF outcomes to explore what disparities existed prior to access of CFTR modulators in Canada.

METHODS

A cross-sectional study of SA and Canadian CF registries data for period 1 January to 31 December 2018. CF registry data were harmonised between countries to compare lung function and nutrition outcomes. Poor nutrition was defined as BMIz-score < -1 in children and < 18.5 kg/m2 in adults. Standardised mean difference (SMD) >10 was considered significant.

RESULTS

After excluding Canadians on CFTR modulators and lung transplant recipients, data on 4049 Canadian and 446 SA people was analysed. Compared to Canada, people in SA were younger (median age 15.8 years vs. 24.1 years: SMD 52) with fewer males (47.8% vs 54.2%; SMD 12.5) and White (70.9% vs. 93.3%; SMD 61.3). Class I-III CFTR mutation frequency was similar in SA (n = 384, 86.1%) and Canada (n = 3426, 84.9%). After adjusting for age, gender, diagnosis age, genotype, P.aeruginosa infection and pulmonary treatments, FEV1pp was 8.9% lower (95% CI 6.3% to 11.4%) and poor nutrition 1.7-fold more common (OR 1.70; 95% CI 1.19-2.41) in SA compared to Canada.

CONCLUSION

Lung function and nutrition was significantly lower in SA compared to Canada. Global disparities in CF outcomes between high and low-middle income countries are likely to widen as CFTR modulators are rapidly scaled up in only high-income countries.

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.

What the future holds: cystic fibrosis and aging

Cystic fibrosis (CF) is one of the most common genetic diseases with around 70,000 affected patients worldwide. CF is a multisystem disease caused by a mutation in the CF transmembrane conductance regulator gene, which has led to a significant decrease in life expectancy and a marked impairment in the quality of life for people with CF (pwCF). In recent years, the use of highly effective CFTR modulator therapy (HEMT) has led to improved pulmonary function, fewer CF exacerbations, lower symptom burden, and increased weight. This has coincided with an increased life expectancy for pwCF, with mean age of survival being now in the 50s. This being a major breakthrough, which the CF population has hoped for, pwCF are now facing new challenges by growing old with a chronic respiratory disease. In this mini review, we are attempting to summarize the current knowledge of the aging process and its effect on CF disease and its manifestations including new developments, the current research gaps and potential future developments in the field to allow healthy aging for the CF community.

The roles and experiences of adolescents with cystic fibrosis and their parents during transition: A qualitative interview study

PURPOSE

Inadequate participation of Adolescents and Young Adults (AYAs) and parents are well-established barriers of transition. Shifts in roles are mandatory with increasing responsibilities for AYAs and decreasing involvement of parents in care. This study explores the shifts in roles of AYAs and their parents and its association with the subjective experience of transition.

METHODS

We conducted in-depth semi-structured interviews with AYAs living with Cystic Fibrosis and parents. Participants were recruited through patient organizations via convenience sampling and questioned on which roles they assumed during transition. Three authors performed an interpretative phenomenological analysis, establishing separate code trees for AYAs and parents. Data saturation was achieved.

RESULTS

18 AYAs (age 21y±2.9) and 14 parents (age 50y±2.0) were included. We identified five common themes: (1) the reciprocal reliance between AYAs and parents, (2) the policies of physicians and hospitals, (3) the AYAs' changing appeal and need for support, (4) the identification of parents as co-patients, and (5) the enforced changes in the roles of parents. AYAs primarily addressed roles related to self-management, while parents discussed family functioning.

CONCLUSIONS

This study identified motives underlying the assumption of roles by AYAs and parents. Both AYAs and parents addressed similar themes, highlighting their mutual challenges and needs. In contrast to AYAs, parents' desired roles were undefined and a latent sense of responsibility was identified as an important motive. Healthcare providers should acknowledge parents' challenging position and communicate transparently about changing roles. Additionally, healthcare providers should recognize that imposing restrictive roles may result in parental resistance, but can also foster AYAs' skill development. Future research should examine the short- and long-term impact of role-management interventions in AYAs and their parents.

Cystic fibrosis

Cystic fibrosis (CF) is an autosomal recessive genetic disease caused by variants in the gene encoding for the cystic fibrosis transmembrane conductance regulator (CFTR) protein. CFTR dysfunction results in abnormal chloride and bicarbonate transport in epithelial cells, leading to a multiorgan disease dominated by respiratory and digestive manifestations. The respiratory disease, which is characterized by airway mucus plugging, chronic bacterial infection and progressive development of bronchiectasis, may lead to chronic respiratory failure, which is the main cause of premature death in people with CF. Over the past 50 years, major progress has been obtained by implementing multidisciplinary care, including nutritional support, airway clearance techniques and antibiotics in specialized CF centers. The past 10 years have further seen the progressive development of oral medications, called CFTR modulators, that partially restore ion transport and lead to a major improvement in clinical manifestations and lung function, presumably resulting in longer survival. Although an increasing proportion of people with CF are being treated with CFTR modulators, challenges remain regarding access to CFTR modulators due to their high cost, and their lack of marketing approval and/or effectiveness in people with rare CFTR variants. The anticipated increase in the number of adults with CF and their aging also challenge the current organization of CF care. The purpose of this review article is to describe current status and future perspective of CF disease and care.

Aiming to Improve Equity in Pulmonary Health: Cystic Fibrosis

This review summarizes the evidence of health disparities in cystic fibrosis (CF), an autosomal recessive genetic disorder with substantial variation in disease progression and outcomes. We review disparities by race, ethnicity, socioeconomic status, geographic location, gender identity, or sexual orientation documented in the literature. We outline the mechanisms that generate and perpetuate such disparities across levels and domains of influence and assess the implications of this evidence. We then recommend strategies for improving equity in CF outcomes, drawing on recommendations for the general population and considering approaches specific to people living with CF.

Elexacaftor - Tezacaftor - Ivacaftor treatment improves systemic infection parameters and Pseudomonas aeruginosa colonization rate in patients with cystic fibrosis a monocentric observational study

Background & aims

The CFTR-modulating therapy Elexaftor - Tezacaftor - Ivacaftor (ETI) has been widely prescribed since its approval in 2020 in the European Union. The aim of this study was to methodically evaluate the effects of an ETI treatment on clinical, biochemical data and Pseudomonas colonization in order to demonstrate its efficacy.

Methods

This prospective monocentric study comprised 69 patients diagnosed with cystic fibrosis aged at least 12 years and treated with ETI between September 2020 and November 2021. Clinical and laboratory data of each patient and study visit were collected before and after 24 weeks of ETI treatment. Follow-up status of Pseudomonas aeruginosa (PsA) colonization was assessed after one year of therapy by regularly determined sputum or throat swab samples.

Results

Marked improvements biochemical markers of systemic inflammation as white blood cell count, levels of immunoglobulins A, G and M and albumin within 24 weeks of therapy were observed. ETI treatment proved to be effective as seen by amelioration of lung function and sweat chloride concentration. Assessment of PsA colonization status revealed a conversion from a positive to negative detection in 36% of the cases after one year of therapy.

Conclusions

ETI treatment effectively improves systemic inflammation parameters and shows promising results in PsA status conversion.

Screening strategies for glucose tolerance abnormalities and diabetes in people with cystic fibrosis

The increase in life expectancy of patients with cystic fibrosis has come with new comorbidities, particularly diabetes. The gradual development of glucose tolerance abnormalities means that 30 to 40% of adults will be diabetic. Cystic fibrosis-related diabetes is a major challenge in the care of these patients because it is a morbidity and mortality factor at all stages of the disease. Early glucose tolerance abnormalities observed from childhood, before the stage of diabetes, are also associated with a poor pulmonary and nutritional outcome. The long asymptomatic period justifies systematic screening with an annual oral glucose tolerance test from the age of 10 years. However, this strategy does not take into account the new clinical profiles of patients with cystic fibrosis, recent pathophysiological knowledge of glucose tolerance abnormalities, and the emergence of new diagnostic tools in diabetology. In this paper, we summarise the challenges of screening in the current context of new patient profiles - patients who are pregnant, have transplants, or are being treated with fibrosis conductance transmembrane regulator modulators - and put forward an inventory of the various screening methods for cystic fibrosis-related diabetes, including their applications, limitations and practical implications.

Sleep-Disordered Breathing and Chronic Respiratory Infections: A Narrative Review in Adult and Pediatric Population

Sleep-disordered breathing (SDB) comprises different diseases characterized by abnormal respiratory patterns during sleep including obstructive sleep apnea. SDB prevalence and impact in patients with chronic respiratory infections have been only marginally studied. The purpose of this narrative review is to report the prevalence and impact of SDB in chronic respiratory infections, including cystic fibrosis (CF), bronchiectasis and mycobacterial infections, and explore the possible pathophysiological mechanisms. Common pathophysiological mechanisms, underlying SDB onset in all chronic respiratory infections, include inflammation, which plays a central role, chronic nocturnal cough and pain, excessive production of mucous plugs, presence of obstructive and/or restrictive ventilatory impairment, upper airways involvement, and comorbidities, such as alteration of nutritional status. SDB may affect about 50% of patients with bronchiectasis. The severity of the disease, e.g., patients colonized with P. aeruginosa and frequent exacerbators, as well as comorbidities, such as chronic obstructive pulmonary disease and primary ciliary dyskinesia, may impact SDB onset. SDB may also frequently complicate the clinical course of both children and adults with CF, impacting the quality of life and disease prognosis, suggesting that their routine assessment should be incorporated into the clinical evaluation of patients from the first stages of the disease regardless of suggestive symptoms, in order to avoid late diagnosis. Finally, although the prevalence of SDB in patients with mycobacterial infections is uncertain, extrapulmonary manifestations, particularly nasopharyngeal locations, and concomitant symptoms, such as body pain and depression, may act as atypical predisposing factors for their development.

Beyond borders: cystic fibrosis survival between Australia, Canada, France and New Zealand

BACKGROUND

Life expectancy for people with cystic fibrosis (CF) varies considerably both within and between countries. The objective of this study was to compare survival among countries with single-payer healthcare systems while accounting for markers of disease severity.

METHODS

This cohort study used data from established national CF registries in Australia, Canada, France and New Zealand from 2015 to 2019. Median age of survival for each of the four countries was estimated using the Kaplan-Meier method. A Cox proportional hazards model was used to compare risk of death between Canada, France and Australia after adjusting for prognostic factors. Due to low number of deaths, New Zealand was not included in final adjusted models.

RESULTS

Between 2015 and 2019, a total of 14 842 people (3537 Australia, 4434 Canada, 6411 France and 460 New Zealand) were included. The median age of survival was highest in France 65.9 years (95% CI: 59.8 to 76.0) versus 53.3 years (95% CI: 48.9 to 59.8) for Australia, 55.4 years (95% CI: 51.3 to 59.2) for Canada and 54.8 years (95% CI: 40.7 to not available) for New Zealand. After adjusting for individual-level factors, the risk of death was significantly higher in Canada (HR 1.85, 95% CI: 1.48 to 2.32; p<0.001) and Australia (HR 2.08, 95% CI: 1.64 to 2.64; p<0.001) versus France.

INTERPRETATION

We observed significantly higher survival in France compared with countries with single-payer healthcare systems. The median age of survival in France exceeded 60 years of age despite having the highest proportion of underweight patients which may be due to differences in availability of transplant.

Association of Oxygen Therapy with the Natural Disease Progression of Cystic Fibrosis: A Multi-State Model of the European Cystic Fibrosis Society Patient Registry

Background

Association between dependence on oxygen therapy (OT) and natural disease progression in people with cystic fibrosis (pwCF) has not been estimated yet. The aim of this study is to understand the prognosis for pwCF on OT, evaluating how the transition probabilities from being alive without lung transplantation (LTx) to LTx and to death, and from being alive after LTx to death change in pwCF with and without OT.

Methods

We used 2008-2017 data from the 35-country European CF Society Patient Registry. A multi-state model was fitted to assess the effects of individual risk factors on transition probabilities.

Results

We considered 48,343 pwCF aged from 6 to 50 years. OT (HR 5.78, 95% CI: 5.32-6.29) and abnormal FEV₁ (HR 6.41, 95% CI: 5.28-7.79) were strongly associated with the probability of having LTx; chronic infection with Burkholderia cepacia complex (HR 3.19, 95% CI: 2.78-3.67), abnormal FEV₁ (HR 5.00, 95% CI: 4.11-6.08) and the need for OT (HR 4.32, 95% CI: 3.93-4.76) showed the greatest association with the probability of dying without LTx. Once pwCF received LTx, OT (HR 1.75, 95% CI: 1.41-2.16) and abnormal FEV₁ (HR 1.63, 95% CI: 1.18-2.25) were the main factors associated with the probability of dying. An association of gross national income with the probability of receiving LTx and with the probability of dying without LTx was also found.

Conclusion

Oxygen therapy is associated with poor survival in pwCF with and without LTx; harmonization of CF care throughout European countries and minimization of the onset of pulmonary gas exchange abnormalities using all available means remains of paramount importance.

Toward a Broader Understanding of Cystic Fibrosis Epidemiology and Its Impact on Clinical Manifestations

The incidence of cystic fibrosis remains constant in North America and Western Europe is 1 in 3500 live births, but survival and quality of life have improved. The cystic fibrosis population has shifted toward the adult age range with a concomitant shift in the spectrum of complications. Survival increased because of aggressive symptomatic therapy, earlier diagnosis by newborn screening, and the introduction of modulators of the cystic fibrosis transmembrane conductance regulator, so that predicted median survival age is now about 50 years. In the United States, members of low socioeconomic status populations or members of racial or ethnic minorities have benefitted less from these advances.

Obstructive sleep apnea and nocturnal hypoxemia in adult patients with cystic fibrosis

Background

Obstructive sleep apnea (OSA), nocturnal hypoxemia and excessive daytime sleepiness (EDS) are common comorbidities in people with cystic fibrosis (pwCF). Most of the data showing this originates from children and adolescents. The aim of this study was to collect data on sleep parameters, EDS and pulmonary function from a large cohort of adult pwCF.

Methods

Full overnight polysomnography (PSG) was performed. EDS was determined using the Epworth Sleepiness Scale (ESS). Demographic and clinical data (body mass index [BMI], pulmonary function, capillary blood gases) were collected.

Results

A total of 52 adult pwCF were included (mean age 30.7 ± 8.0 years, mean percent predicted forced expiratory volume in 1 s [ppFEV1] of 52.1 ± 14.8). Overall AHI was in the normal range (4.5 ± 4.0/h); 21/52 pwCF (40%) had an apnea-hypopnea index > 5/h. Nocturnal hypoxemia was found in 25% of participants and this was associated with ppFEV1 (p = 0.014), awake oxygen saturation (SpO2; p = 0.021) and awake partial pressure of oxygen (pO2; p = 0.003); there were no significant differences in age, lung function and BMI were found for pwCF with versus without OSA (all p > 0.05). Eight pwCF (15%) had an ESS score > 10 (indicating EDS). OSA was best predicted by awake pO2 (area under the curve [AUC] 0.66, p = 0.048), while nocturnal hypoxemia was best predicted by ppFEV1 (AUC 0.74, p = 0.009), awake pO2 (AUC 0.76, p = 0.006) and awake SpO2 (AUC 0.71; p = 0.025).

Conclusion

OSA, nocturnal hypoxemia and EDS were common in adult pwCF, but no strong predictors were identified. Therefore, we suggest regular PSG and ESS scoring in adult pwCF, regardless of disease severity.

Membrane lipid renovation in Pseudomonas aeruginosa - implications for phage therapy?

Pseudomonas aeruginosa is an important Gram-negative pathogen with intrinsic resistance to many clinically used antibiotics. It is particularly troublesome in nosocomial infections, immunocompromised patients, and individuals with cystic fibrosis. Antimicrobial resistance (AMR) is a huge threat to global health, with a predicted 10 million people dying from resistant infections by 2050. A promising therapy for combatting AMR infections is phage therapy. However, more research is required to investigate mechanisms that may influence the efficacy of phage therapy. An important overlooked aspect is the impact of membrane lipid remodelling on phage binding ability. P. aeruginosa undergoes changes in membrane lipids when it encounters phosphorus stress, an environmental perturbation that is likely to occur during infection. Lipid changes include the substitution of glycerophospholipids with surrogate glycolipids and the over-production of ornithine-containing aminolipids. Given that membrane lipids are known to influence the structure and function of membrane proteins, we propose that changes in the composition of membrane lipids during infection may alter phage binding and subsequent phage infection dynamics. Consideration of such effects needs to be urgently prioritised in order to develop the most effective phage therapy strategies for P. aeruginosa infections.

Palliative care services for children with life-limiting conditions

BACKGROUND

Palliative care (PC) for children with life-limiting conditions (LLC) is a holistic approach to achieve the best quality of life.

AIMS

Highlighting collaboration between pediatric and PC services is essential in providing seamless care.

METHODS

Retrospective data obtained including patient cohort, disease profile, place of death, and the resource requirements for children with a LLC in the Mid-West region of Ireland over a 7-year period.

RESULTS

Seventy-seven patients were identified (n = 77); five still receiving care, four discharged, and 68 have died. The cohort ranged in age from 1 day to 17 years with a mean of approximately 6 years. Thirty-five percent of patients were less than 1 year old. Fifty-one percent were male. Seventy-one percent were referred initially to PC for end-of-life care and 29% for symptom management. Forty-four percent had home support services in place prior to referral to PC. An advanced care plan was created for 65%. Of those that died (n = 68), 70.5% died at home, 25% in hospital, and 4.4% in residential care or a children's hospice. The clinical nurse coordinator for children with life-limiting conditions (CNCCLLC) was involved with 88% of patients. The specialist PC teams were involved with 87%; 65 patients had community support, 31 patients had in-hospital support, and 29 patients were seen by both hospital and community services.

CONCLUSIONS

Our study highlights the growing number of LLCs and current pediatric and PC services require further resources and development.

Socioeconomic determinants of respiratory health in patients with cystic fibrosis: implications for treatment strategies

INTRODUCTION

Great variation exists in the progression and outcomes of cystic fibrosis (CF) lung disease, due to both genetic and environmental influences. Social determinants mediate environmental exposures and treatment success; people with CF from socioeconomically disadvantaged backgrounds have worse health and die younger than those in more advantaged positions.

AREAS COVERED

This paper reviews the literature on the mechanisms that are responsible for generating and sustaining disparities in CF health, and the ways by which social determinants translate into health advantages or disadvantages in people with CF. The authors make recommendations for addressing social risk factors in CF clinical practice.

EXPERT OPINION

Socioeconomic factors are not dichotomous and their impact is felt at every step of the social ladder. CF care programs need to adopt a systematic protocol to screen for health-related social risk factors, and then connect patients to available resources to meet individual needs. Considerations such as daycare, schooling options, living and working conditions, and opportunities for physical exercise and recreation as well as promotion of self-efficacy are often overlooked. In addition, advocacy for changes in public policies on health insurance, environmental regulations, social welfare, and education would all help address the root causes of CF health inequities.

Trends in cystic fibrosis survival over 40 years in South Africa: An observational cohort study

INTRODUCTION

Temporal trends in cystic fibrosis (CF) survival from low-middle-income settings is poorly reported. We describe changes in CF survival after diagnosis over 40 years from a South African (SA) CF center.

METHODS

An observational cohort study of people diagnosed with CF from 1974 to 2019. Changes in age-specific mortality rates from 2000 (vs. before 2000) were estimated using multivariable Poisson regression. Data were stratified by current age < or ≥10 years and models controlled for diagnosis age, sex, ethnicity, genotype, and Pseudomonas aeruginosa (PA) infection. A second analysis explored the association of mortality with weight and forced expiratory volume in 1 s reported as z-scores (FEV1z-scores) at age 5-8 years.

RESULTS

A total of 288 people (52% male; 57% Caucasian; 44% p.Phe508del homozygous) were included (median diagnosis age 0.5 years: Q1, Q3: 0.2, 2.5); 100 (35%) died and 30 (10%) lost to follow-up. Among age >10 years, age-specific mortality from 2000 was significantly lower (adjusted hazard ratio [aHR]: 0.14; 95% confidence interval [CI]: 0.06, 0.29; p < 0.001), but not among age <10 years (aHR: 0.67; 95% CI: 0.28, 1.64; p = 0.383). In children <10 years, Caucasian ethnicity was associated with lower mortality (aHR 0.17; 95% CI: 0.05, 0.63), and longer times since first PA infection with higher mortality (aHR: 1.31; 95% CI: 1.01, 1.68). Mortality was sevenfold higher if FEV1z was <-2.0 at age 5-8 years (aHR: 7.64; 95% CI: 2.58, 22.59).

CONCLUSION

Overall, CF survival has significantly improved in SA from 2000 in people older than 10 years. However, increased risk of mortality persists in young non-Caucasian children, and with FEV1z <-2.0 at age 5-8 years.

Effects of Elexacaftor/Tezacaftor/Ivacaftor Therapy on CFTR Function in Patients with Cystic Fibrosis and One or Two F508del Alleles

RATIONALE

The CFTR modulator combination elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) was shown to improve clinical outcomes and sweat chloride concentration (SCC) in patients with cystic fibrosis (CF) and one or two F508del alleles. However, the effect of ELX/TEZ/IVA on CFTR function in the airways and intestine has not been studied.

OBJECTIVES

To assess the effect of ELX/TEZ/IVA on CFTR function in airway and intestinal epithelia in patients with CF and one or two F508del alleles aged 12 years and older.

METHODS

This prospective observational multicenter study assessed clinical outcomes including FEV1 %predicted and body mass index, and the CFTR biomarkers SCC, nasal potential difference (NPD) and intestinal current measurement (ICM) before and 8-16 weeks after initiation of ELX/TEZ/IVA.

MEASUREMENTS AND MAIN RESULTS

A total of 107 patients with CF including 55 patients with one F508del and a minimal function mutation and 52 F508del homozygous patients were enrolled in this study. In patients with one F508del allele, NPD and ICM showed that ELX/TEZ/IVA improved CFTR function in nasal epithelia to a level of 46.5% (IQR, 27.5-72.4; P<0.001) and in intestinal epithelia to 41.8% of normal (IQR, 25.1-57.6; P<0.001). In F508del homozygous patients, ELX/TEZ/IVA exceeded improvement of CFTR function observed with TEZ/IVA and increased CFTR-mediated Cl- secretion to a level of 47.4% of normal (IQR, 19.3-69.2; P<0.001) in nasal and to 45.9% (IQR, 19.7-66.6; P<0.001) in intestinal epithelia.

CONCLUSIONS

Treatment with ELX/TEZ/IVA results in effective improvement of CFTR function in airway and intestinal epithelia in patients with CF and one or two F508del alleles.

Consistent Assignment of Risk and Benign Allele at rs2303153 in the CF Modifier Gene SCNN1B in Three Independent F508del-CFTR Homozygous Patient Populations

CFTR encodes for a chloride and bicarbonate channel expressed at the apical membrane of polarized epithelial cells. Transepithelial sodium transport mediated by the amiloride-sensitive sodium channel ENaC is thought to contribute to the manifestation of CF disease. Thus, ENaC is a therapeutic target in CF and a valid cystic fibrosis modifier gene. We have characterized SCNN1B as a genetic modifier in the three independent patient cohorts of F508del-CFTR homozygotes. We could identify a regulatory element at SCNN1B to the genomic segment rs168748-rs2303153-rs4968000 by fine-mapping (Pbest = 0.0177), consistently observing the risk allele rs2303153-C and the contrasting benign allele rs2303153-G in all three patient cohorts. Furthermore, our results show that expression levels of SCNN1B are associated with rs2303153 genotype in intestinal epithelia (p = 0.003). Our data confirm that the well-established biological role of SCNN1B can be recognized by an association study on informative endophenotypes in the rare disease cystic fibrosis and calls attention to reproducible results in association studies obtained from small, albeit carefully characterized patient populations.