Cystic fibrosis transmembrane conductance regulator-related metabolic syndrome/cystic fibrosis screen positive, inconclusive diagnosis (CRMS/CFSPID)

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.

International Perspectives of Extended Genetic Sequencing When Used as Part of Newborn Screening to Identify Cystic Fibrosis

There is increasing interest in using extended genetic sequencing (EGS) in newborn screening (NBS) for cystic fibrosis (CF). How this is implemented will change the number of children being given an uncertain outcome of CRMS/CFSPID (cystic fibrosis transmembrane conductance regulator (CFTR)-related metabolic syndrome/CF Screen Positive Inconclusive Diagnosis), probable carrier results, and the number of missed CF diagnoses. An international survey of CF health professionals was used to gather views on two approaches to EGS-specific (may reduce detection of CRMS/CFSID but miss some CF cases) versus sensitive (may increase detection of CRMS/CFSPID but avoid missing more CF cases). Health professionals acknowledged the anxiety caused to parents (and health professionals) from the uncertainty surrounding the prognosis and management of CRMS/CFSPID. However, most preferred the sensitive approach, as overall, identifying more cases of CRMS/CFSPID was viewed as less physically and psychologically damaging than a missed case of CF. The importance of early diagnosis and treatment for CF to ensure better health outcomes and reducing diagnostic odysseys for parents were highlighted. A potential benefit to identifying more children with CRMS/CFSPID included increasing knowledge to obtain a better understanding of how these children should best be managed in the future.

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

OBJECTIVES

Universal implementation of cystic fibrosis (CF) newborn screening (NBS) has led to the diagnostic dilemma of infants with CF screen-positive, inconclusive diagnosis (CFSPID), with limited guidance regarding prognosis and standardized care. Rates of reclassification from CFSPID to CF vary and risk factors for reclassification are not well established. We investigated whether clinical characteristics are associated with the risk of reclassification from CFSPID to a CF diagnosis.

METHODS

Children with a positive CF NBS were recruited from two sites in California. Retrospective, longitudinal, and cross-sectional data were collected. A subset of subjects had nasal epithelial cells collected for CF transmembrane conductance regulator (CFTR) functional assessment. Multivariate logistic regression was used to assess the risk of reclassification.

RESULTS

A total of 112 children completed the study (CF = 53, CFSPID = 59). Phenotypic characteristics between groups showed differences in pancreatic insufficiency prevalence, immunoreactive trypsinogen (IRT) levels, and Pseudomonas aeruginosa (PSA) colonization. Spirometry measures were not different between groups. Nasal epithelial cells from 10 subjects showed 7%-30% of wild-type (WT)-CFTR (wtCFTR) function in those who reclassified and 27%-67% of wtCFTR function in those who retained the CFSPID designation. Modeling revealed that increasing sweat chloride concentration (sw[Cl^- ]) and PSA colonization were independent risk factors for reclassification to CF.

CONCLUSION

Increasing sw[Cl^- ] and a history of PSA colonization are associated with the risk of reclassification from CFSPID to CF in a population with high IRT and two CFTR variants. A close follow-up to monitor phenotypic changes remains critical in this population. The role of CFTR functional assays in this population requires further exploration.

A Multicentre Italian Study on the Psychological Impact of an Inconclusive Cystic Fibrosis Diagnosis after Positive Neonatal Screening

BACKGROUND

An inconclusive diagnosis of cystic fibrosis (CF) after positive newborn screening (NBS) may cause parental distress. We compared the psychological impact of CF transmembrane conductance regulator-related metabolic syndrome (CRMS)/CF screen-positive, inconclusive diagnosis (CFSPID), and clear CF diagnosis, on parents.

METHODS

The participants were administered the Generalized Anxiety Disorder Scale, Patient Health Questionnaire-9, and the Italian version of the Impact of Event Scale-Revised as quantitative tools and semi-structured interviews as qualitative tools. Parental experience, child representation, relationships, future information, and perception of health status were investigated. Interviews were recorded and transcribed verbatim maintaining anonymity.

RESULTS

Thirty-two families were enrolled: sixteen with CF and CRMS/CFSPID, respectively. Anxiety and depression values were high in both groups, as were the measurement of traumatic impact subscales: avoidance, intrusiveness, and hyperarousal. The children's health was evaluated by respective parents as being nearly healthy.

CONCLUSIONS

Our results highlight negative psychological impacts, including emotional and affective representations, on parents of children with inconclusive CF diagnosis compared with those with clear diagnosis.

Outcomes of children with cystic fibrosis screen positive, inconclusive diagnosis/CFTR related metabolic syndrome

Background

Some infants undergoing newborn screening (NBS) tests have inconclusive sweat chloride test (SCT) results that lead to the designation of Cystic Fibrosis Screen Positive, Inconclusive Diagnosis/CFTR-related metabolic syndrome (CFSPID/CRMS). Some proportion of them transition to a CF diagnosis, but no predictive markers can stratify which are at risk for this transition. We report single-center outcomes of children with CRMS.

Methods

We retrospectively identified all infants born in Alabama from 2008 through 2020 referred to our CF Center with an elevated immunoreactive trypsinogen level (IRT) associated with a cystic fibrosis transmembrane conductance regulator (CFTR) mutation (IRT+/DNA+) who had at least one SCT result documented. Infants were classified per established guidelines as Carrier, CRMS, or CF based on the IRT+/DNA+ and SCT results. The electronic health record was reviewed for follow-up visits until the children received a definitive diagnosis (to carrier or CF) according to current diagnostic guidelines for CF, or through the end of the 2020 year.

Results

Of the 1,346 infants with IRT+ and at least 1 CFTR mutation identified (IRT+/DNA+), 63 (4.7%) were designated as CRMS. Of these infants, 12 (19.1%) transitioned to Carrier status (CRMS-Carrier), 40 (63.5%) of them remained CRMS status (CRMS-Persistent) and 11 (17.5%) of them transitioned to a diagnosis of CF (CRMS-CF). Of the 11 children in the CRMS-CF group, 4 (36%) had an initial SCT 30-39 mmol/L, 4 (36%) had an initial SCT 40-49 mmol/L and 3 (27%) had an initial SCT 50-59 mmol/L. These children also had higher initial sweat tests and greater yearly increases in sweat chloride values than others with CRMS. We found that in comparison to children in the CRMS-P group, a greater proportion of children in the CRMS-CF group cultured bacteria like methicillin-resistant Staphylococcus aureus, Stenotrophomonas maltophilia, and Pseudomonas aeruginosa, had smaller weight-for-height percentiles and remained smaller over time despite slightly greater growth.

Conclusion

Infants with an inconclusive diagnosis of CF should continue to receive annual care and management given their potential risk of transition to CF. Further research is needed to assess whether certain phenotypic patterns, clinical symptoms, diagnostic tests or biomarkers could better stratify these children.

Vitamin Status in Children with Cystic Fibrosis Transmembrane Conductance Regulator Gene Mutation

Background: The issue of vitamin metabolism in children with cystic fibrosis screen positive, inconclusive diagnosis (CFSPID) is not well known. The aim of this study was to determine the status of vitamins A, D, E, and C in the blood of a group of children with CFSPID. Material and Methods: A total of 89 children were enrolled in the study (Me: 3.6 years, 52.8% boys), as follows: 28 with CFSPID, 31 with CF (cystic fibrosis), and 30 HC (healthy children). Their blood concentrations of vitamins A, D, E, and C, and their dietary intake of these vitamins were analysed in the study groups on the basis of a three-day food diary. Results: The patients with CFSPID had significantly higher serum vitamin D (p = 0.01) and E (p = 0.04) concentrations, compared to the children with CF. None of the children with CFSPID revealed vitamin A or E deficiencies. Patients with CF had been consuming significantly higher vitamin D and E amounts (p = 0.01). The vitamin concentrations did not depend either on the pancreatic/liver function or on anthropometric parameters. In total, 32.14% of patients with CF did not cover the baseline recommended calorie intake, and 53.6% and 36% did not take the recommended vitamin E and vitamin A intake, respectively. Conclusion: Children with CF and CFSPID did not fully cover the dietary recommendations for vitamin supply, but vitamin deficiency was found only in CF.

International Approaches to Management of CFTR-Related Metabolic Syndrome/Cystic Fibrosis Screen Positive, Inconclusive Diagnosis

The main aim of the present study was to explore health professionals' reported experiences and approaches to managing children who receive a designation of cystic fibrosis transmembrane conductance regulator-related metabolic syndrome/cystic fibrosis screen positive inconclusive diagnosis following a positive NBS result for cystic fibrosis. An online questionnaire was distributed via Qualtrics Survey Software and circulated to a purposive, international sample of health professionals involved in managing children with this designation. In total, 101 clinicians completed the online survey: 39 from the US, six from Canada, and 56 from Europe (including the UK). Results indicated that while respondents reported minor deviations in practice, they were cognizant of recommendations in the updated guidance and for the most part, attempted to implement these into practice consistently internationally. Where variation was reported, the purpose of this appeared to be to enable clinicians to respond to either clinical assessments or parental anxiety in order to improve outcomes for the child and family. Further research is needed to determine if these findings are reflective of both a wider audience of clinicians and actual (rather than reported) practice.