title: Outcomes of infants with indeterminate diagnosis detected by cystic fibrosis newborn screening.
abstract: OBJECTIVE
  Cystic fibrosis transmembrane conductance regulator-related metabolic syndrome (CRMS) describes asymptomatic infants with a positive cystic fibrosis (CF) newborn screen (NBS) but inconclusive diagnostic testing for CF. Little is known about the epidemiology and outcomes of CRMS. The goal of this study was to determine the prevalence, clinical features, and short-term outcomes of infants with CRMS.
  
  
  METHODS
  We analyzed data from the US CF Foundation Patient Registry (CFFPR) from 2010 to 2012. We compared demographic, diagnostic, anthropometric, health care utilization, microbiology, and treatment characteristics between infants with CF and infants with CRMS.
  
  
  RESULTS
  There were 1983 infants diagnosed via NBS between 2010 and 2012 reported to the CFFPR. By using the CF Foundation guideline definitions, 1540 and 309 infants met the criteria for CF and CRMS, respectively (CF:CRMS ratio = 5.0:1.0). Of note, 40.8% of infants with CRMS were entered into the registry with a clinical diagnosis of CF. Infants with CRMS tended to have normal nutritional indices. However, 11% of infants with CRMS had a positive Pseudomonas aeruginosa respiratory tract culture in the first year of life.
  
  
  CONCLUSIONS
  CRMS is a common outcome of CF NBS, and some infants with CRMS may develop features concerning for CF disease. A substantial proportion of infants with CRMS were assigned a clinical diagnosis of CF, which may reflect misclassification or clinical features not collected in the CFFPR.
authors.affiliation: Division of Pediatric Pulmonology, Department of Pediatrics, University of Rochester, Rochester, New York; clement_ren@urmc.rochester.edu.
authors.forename: Clement L
authors.initials: CL
authors.lastname: Ren
authors.affiliation: Cystic Fibrosis Foundation, Bethesda, Maryland;
authors.forename: Aliza K
authors.initials: AK
authors.lastname: Fink
authors.affiliation: Cystic Fibrosis Foundation, Bethesda, Maryland;
authors.forename: Kristofer
authors.initials: K
authors.lastname: Petren
authors.affiliation: Division of Pediatric Pulmonology, Department of Pediatrics, Women and Children's Hospital of Buffalo, Buffalo, New York;
authors.forename: Drucy S
authors.initials: DS
authors.lastname: Borowitz
authors.affiliation: Department of Pediatrics, Northwestern University Feinberg School of Medicine and the Ann and Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois;
authors.forename: Susanna A
authors.initials: SA
authors.lastname: McColley
authors.affiliation: Division of Pediatric Pulmonology, Cystic Fibrosis, and Sleep Medicine/Department of Pediatrics, University of Wisconsin, Madison, Wisconsin; and.
authors.forename: Don B
authors.initials: DB
authors.lastname: Sanders
authors.affiliation: Division of Pulmonary Medicine, Seattle Children's Hospital and Department of Pediatrics, University of Washington School of Medicine, Seattle, Washington.
authors.forename: Margaret
authors.initials: M
authors.lastname: Rosenfeld
authors.affiliation: Cystic Fibrosis Foundation, Bethesda, Maryland;
authors.forename: Bruce C
authors.initials: BC
authors.lastname: Marshall
mesh_terms: D003550:Cystic Fibrosis / Q000175:diagnosis* / Q000453:epidemiology / Q000628:therapy; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D015997:Neonatal Screening; D011237:Predictive Value of Tests; D015995:Prevalence; D015203:Reproducibility of Results; D016896:Treatment Outcome
chemical_list: D019005:Cystic Fibrosis Transmembrane Conductance Regulator