Gradual increase in sweat chloride concentration is associated with a higher risk of CRMS/CFSPID to CF reclassification

Advances in Care and Outcomes for Children with Cystic Fibrosis

The landscape of care for children with cystic fibrosis (CF), a genetic disorder of chloride transport with multisystem manifestations including inspissated mucus, recurrent sinopulmonary infections, obstructive lung disease, and exocrine pancreatic insufficiency, is rapidly changing. Early diagnosis via newborn screening enabling timely nutritional support, chronic therapies to improve mucociliary clearance, and prompt treatment of pulmonary infections have improved overall outcomes in children with CF. More widespread availability of novel cystic fibrosis transmembrane conductance regulator modulator therapies for children continues to revolutionize pediatric CF care.However, significant challenges exist to optimize care and outcomes for all children with CF.

Update on advances in cystic fibrosis towards a cure and implications for primary care clinicians

During the past quarter century, the diagnosis and treatment of cystic fibrosis (CF) have been transformed by molecular sciences that initiated a new era with discovery of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The knowledge gained from that breakthrough has had dramatic clinical impact. Although once a diagnostic dilemma with long delays, preventable deaths, and irreversible pathology, CF can now be routinely diagnosed shortly after birth through newborn screening programs. This strategy of pre-symptomatic identification has eliminated the common diagnostic "odyssey" that was a failure of the healthcare delivery system causing psychologically traumatic experiences for parents. Therapeutic advances of many kinds have culminated in CFTR modulator treatment that can reduce the effects of or even correct the molecular defect in the chloride channel -the basic cause of CF. This astonishing advance has transformed CF care as described fully herein. Despite this impressive progress, there are challenges and controversies in the delivery of care. Issues include how best to achieve high sensitivity newborn screening with acceptable specificity; what course of action is appropriate for children who are identified through the unavoidable incidental findings of screening tests (CFSPID/CRMS cases and heterozygote carriers); how best to ensure genetic counseling; when to initiate the very expensive but life-saving CFTR modulator drugs; how to identify new CFTR modulator drugs for patients with non-responsive CFTR variants; how to adjust other therapeutic modalities; and how to best partner with primary care clinicians. Progress always brings new challenges, and this has been evident worldwide for CF. Consequently, this article summarizes the major advances of recent years along with controversies and describes their implications with an international perspective.

Cystic Fibrosis Foundation Evidence-Based Guideline for the Management of CRMS/CFSPID

A multidisciplinary committee developed evidence-based guidelines for the management of cystic fibrosis transmembrane conductance regulator-related metabolic syndrome/cystic fibrosis screen-positive, inconclusive diagnosis (CRMS/CFSPID). A total of 24 patient, intervention, comparison, and outcome questions were generated based on surveys sent to people with CRMS/CFSPID and clinicians caring for these individuals, previous recommendations, and expert committee input. Four a priori working groups (genetic testing, monitoring, treatment, and psychosocial/communication issues) were used to provide structure to the committee. A systematic review of the evidence was conducted, and found numerous case series and cohort studies, but no randomized clinical trials. A total of 30 recommendations were graded using the US Preventive Services Task Force methodology. Recommendations that received ≥80% consensus among the entire committee were approved. The resulting recommendations were of moderate to low certainty for the majority of the statements because of the low quality of the evidence. Highlights of the recommendations include thorough evaluation with genetic sequencing, deletion/duplication analysis if <2 disease-causing variants were noted in newborn screening; repeat sweat testing until at least age 8 but limiting further laboratory testing, including microbiology, radiology, and pulmonary function testing; minimal use of medications, which when suggested, should lead to shared decision-making with families; and providing communication with emphasis on social determinants of health and shared decision-making to minimize barriers which may affect processing and understanding of this complex designation. Future research will be needed regarding medication use, antibiotic therapy, and the use of chest imaging for monitoring the development of lung disease.

Risk of CFTR-related disorders and cystic fibrosis in an Italian cohort of CRMS/CFSPID subjects in preschool and school age

The identification of cystic fibrosis screening-positive, inconclusive diagnosis (CFSPID) in infants is a controversial outcome of newborn screening for cystic fibrosis (CF). Today, despite improvements in the knowledge of CFSPID and the description of several cohorts, little data are available on cohorts with a follow-up period of more than 6 years. In this study, we report the outcomes of an Italian cohort of CFSPID individuals with CFSPID or formerly CFTR-related disorders (CFTR-RD) (CFSPID > CFTR-RD) or diagnosed with CF (CFSPID > CF). This was an observational and multicentre Italian study collecting clinical data on CFSPID born between the period January 1, 2011, and December 13, 2019. A total of 268 participants were included: 243 with persistent CFSPID, 7 with CFSPID > CFTR-RD, and 18 with CFSPID > CF. The trend of sweat chloride (SC) values, percentage of definitive diagnoses, lung function in school-aged children, and development of CF-related complications were evaluated. At the end of the observation period, almost 80% of the individuals with CFSPID did not have a conclusive diagnosis. A total of 29 children (10.8%) transitioned to a diagnosis of CF for pathological SC values (≥ 60 mmol/L) or multi-organ involvement, and 18 (6.7%) to CFTR-RD. Children who were followed up for > 6 years (median age, 7.5 years; range, 6.04-10.5) had normal lung function and were pancreatic sufficient, and the evolution in CF was only present in two cases.

CONCLUSION

Most Italian preschool and school-aged children with CFSPID did not have a conclusive diagnosis, and progression to CF was unlikely in children > 6 years of age. An annual follow-up could be indicated to identify early evolution in clinical features consistent with a CFTR-RD.

WHAT IS KNOWN

• Cystic Fibrosis newborn screening identifies also subjects with an inconclusive diagnosis (CFSPID). • Over time a variable percentage of CFSPIDs will be diagnosed as CF. • Little data is available on CFSPIDs with a follow-up period of more than six years.

WHAT IS NEW

• 80% of Italian preschool and school-age CFSPIDs not have a conclusive diagnosis. • Italian preschool and school-age CFSPIDs have normal lung function and are pancreatic sufficient. • Annual follow-up after 6 years is recommended in CFSPID with abnormal LCI2.5 or with a CF-causing variant in trans with a VVCC.

Biochemical and genetic tools to predict the progression to Cystic Fibrosis in CRMS/CFSPID subjects: A systematic review

OBJECTIVES

Aim of this study was to identify risk factors for a progression to cystic fibrosis (CF) in individuals detected as CF Screening Positive, Inconclusive Diagnosis (CFSPID).

METHODS

This is a systematic review through literature databases (2015-2023). Blood immunoreactive trypsinogen (b-IRT) values, CFTR genotype, sweat chloride (SC) values, isolation of Pseudomonas aeruginosa (Pa) from respiratory samples, Lung Clearance Index (LCI) values in CFSPIDs who converted to CF (CFSPID > CF) and age at CF transition were assessed.

RESULTS

Percentage of CFSPID > CF varies from 5.3 % to 44 %. Presence of one CF-causing CFTR variant in trans with a variant with variable clinical consequences (VVCC), an initial SC ≥ 40 mmol/L, an increase of SC > 2.5 mmol/L/year and recurrent isolation of pseudomonas aeruginosa (Pa) from airway samples could allow identification of subjects at risk of progression to CF.

CONCLUSIONS

CFSPIDs with CF causing variant/VVCC genotype and first SC in the higher borderline range may require more frequent and prolonged clinical follow-up.

Cystic fibrosis year in review 2022

Remarkable medical advancements have been made for people with cystic fibrosis (CF) in recent years, with an abundance of research continuing to be conducted worldwide. With concern for limitations in access to highly effective CFTR modulators, as well as the recent Coronavirus Disease-19 pandemic, there has been a consistent effort to understand and improve CF screening, disease burden, diagnosis, and management. Our aim in this review is to present articles from 2022 with an emphasis on clinically relevant studies. We hope this will serve as a broad overview of the research published in the past year.

Cystic Fibrosis screen positive, inconclusive diagnosis (CFSPID) to Cystic Fibrosis: Detecting disease with serial assessments

We present the case of a child given a CFSPID designation in early life who was later reclassified as having CF based on a combination of recurrent respiratory symptoms and CFTR functional testing, despite normal sweat chloride levels. Here we demonstrate the importance of monitoring these children, each time reviewing the diagnosis based on updated understanding of individual CFTR mutation phenotypes or clinical findings inconsistent with the designation. This case identifies situations in which the CFSPID designation should be challenged, and gives an approach for this when CF is suspected.

Comparison between Gibson-Cooke and Macroduct Methods in the Cystic Fibrosis Neonatal Screening Program and in Subjects Who Are Cystic Fibrosis Screen-Positive with an Inconclusive Diagnosis

The sweat test (ST) is the current diagnostic gold standard for cystic fibrosis (CF). Many CF centres have switched from the Gibson-Cooke method to the Macroduct system-based method. We used these methods simultaneously to compare CF screening outcomes. STs using both methods were performed simultaneously between March and December 2022 at CF Centre in Florence. We included newborns who underwent newborn bloodspot screening (NBS), newborns undergoing transfusion immediately after birth, and children with CF screen-positive, inconclusive diagnosis (CFSPID). We assessed 72 subjects (median age 4.4 months; range 0-76.7): 30 (41.7%) NBS-positive, 18 (25.0%) newborns who underwent transfusion, and 24 (33.3%) children with CFSPID. No significant differences were found between valid sample numbers, by patient ages and groups (p = 0.10) and between chloride concentrations (p = 0.13), except for sweat chloride (SC) measured by the Gibson-Cooke and Macroduct methods in CFSPID group (29.0, IQR: 20.0-48.0 and 22.5, IQR: 15.5-30.8, respectively; p = 0.01). The Macroduct and Gibson-Cooke methods showed substantial agreement with the SC values, except for CFSPID, whose result may depend on the method of sweat collection. In case of invalid values with Macroduct, the test should be repeated with Gibson-Cooke method.

Lung clearance index in children with cystic fibrosis previously diagnosed with CRMS/CFSPID: A monocentric prospective experience

INTRODUCTION

No data are available on the values and role of lung clearance index (LCI) in cystic fibrosis (CF) Screen Positive Inconclusive Diagnosis (CFSPID) progressed to CF diagnosis (CFSPID > CF). This study aimed to assess the value of the LCI in correctly predicting the progression of CFSPID to CF.

METHODS

This is a prospective study carried out at the CF Regional Center of Florence, Italy from September 1, 2019. We compared LCI values in children with CF diagnosed for positive newborn screening (NBS), CFSPID or CFSPID > CF for pathological sweat chloride (SC). The Exhalyzer-D (EcoMedics AG, Duernten, Switzerland, software version 3.3.1) was used to conduct the LCI tests, every 6 months on stable children.

RESULTS

Forty-two cooperating children were enrolled (mean age at LCI tests: 5.4 years, range: 2.7-8.7): 26 (62%) had CF, 8 (19%) were CFSPID > CF for positive SC, while 8 (19%) kept the CFSPID label at last LCI test. The mean LCI value for patients with CF (7.39; 5.98-10.24) was statistically higher compared to both the mean LCI in the CFSPID > CF (6.62; 5.69-7.58) and in CFSPID (6.56; 5.64-7.21).

CONCLUSIONS

Most of asymptomatic CFSPID or progressed to CF have normal LCI. Further data on the longitudinal course of LCI during follow up of CFSPID and on larger cohorts is needed.

Variability of the sweat test in children with Cystic Fibrosis previously CRMS/CFSPID: A retrospective monocenter experience

Some studies have evaluated the sweat test (ST) intra individual variability in CRMS/CFSPID. Here, we retrospectively evaluated this in a cohort followed at the CF center in Florence, Italy. We enrolled 37 CRMS/CFSPID and 37 CF children, born between 2011 and 2019. A total of 327 ST were retrospectively recovered, of which 17 (5.2%) were quantity not sufficient. After a median follow-up of 33.8 months (range 1.7-88.2), 11 (24.3%) became CF with at least two pathological sweat chloride (SC) values at a median age of 46.9 months (range 1.4-49). The coefficient of variation was 6.2% in CF patients and 32.5% in the CRMS/CFSPID that transitioned to CF (P<.001). Our data highlight a more variability of SC values in CRMS/CFSPID, especially in those that transitioned to a diagnosis of CF. Further studies are needed to understand whether it is correct to define an asymptomatic CRMS/CFSPID with pathological SC as CF.