title: Long-term outcomes of children with intermediate sweat chloride values in infancy.
abstract: OBJECTIVE
  To describe the clinical course of children who have intermediate sweat chloride values on initial screening for cystic fibrosis (CF).
  
  
  METHODS
  We performed a retrospective review of children with intermediate sweat chloride values (raised immunoreactive trypsinogen/1 copy of p.F508del CF mutation on newborn screening (NBS)/sweat chloride value of 30-59 mmol/L) presenting to The Children's Hospital at Westmead over 15 years. Patients with an intermediate sweat chloride evolving to a formal diagnosis of CF (termed "delayed CF") were matched (2:1) with NBS positive patients with CF (termed "NBS positive CF"). Clinical outcomes were compared.
  
  
  RESULTS
  Fourteen of 29 (48%, 95% CI 0.3-0.66) patients with intermediate sweat chloride value evolved to a diagnosis of CF and were matched with 28 NBS positive patients with CF. Delayed CF had less pancreatic insufficiency (OR 0.06, 95% CI 0.01-0.44, P = .006), less colonization with nonmucoid Pseudomonas aeruginosa (OR 0.04, 95% CI 0.01-0.38, P = .005), milder obstructive lung disease (forced expiratory volume in 1 second/forced vital capacity ratio), and overall disease severity (Shwachman scores) at 10 years (mean difference 5.93, 95% CI 0.39-11.46, P = .04; mean difference 4.72, 95% CI 0.9-8.53, P = .015, respectively). Nutritional outcomes were better at 2 years for delayed CF but did not persist to later ages.
  
  
  CONCLUSIONS
  In this cohort, approximately one-half of infants with intermediate sweat chloride value were later diagnosed with CF. The clinical course of delayed CF was milder in some aspects compared with NBS positive CF. These results emphasize the importance of ongoing follow-up of infants with intermediate sweat chloride values.
authors: Sydney Medical School, University of Sydney, New South Wales, Australia; Department of Respiratory Medicine, The Children's Hospital at Westmead, New South Wales, Australia. Electronic address: tgro4924@uni.sydney.edu.au.
authors: Tyler
authors: T
authors: Groves
authors: Department of Respiratory Medicine, The Children's Hospital at Westmead, New South Wales, Australia; Discipline of Pediatrics and Child Health, Sydney Medical School, University of Sydney, New South Wales, Australia.
authors: Paul
authors: P
authors: Robinson
authors: Discipline of Pediatrics and Child Health, Sydney Medical School, University of Sydney, New South Wales, Australia; New South Wales Newborn Screening Program, The Children's Hospital at Westmead, New South Wales, Australia.
authors: Veronica
authors: V
authors: Wiley
authors: Department of Respiratory Medicine, The Children's Hospital at Westmead, New South Wales, Australia; Discipline of Pediatrics and Child Health, Sydney Medical School, University of Sydney, New South Wales, Australia.
authors: Dominic A
authors: DA
authors: Fitzgerald
mesh_terms: D002675:Child, Preschool; D002712:Chlorides / Q000032:analysis*; D003550:Cystic Fibrosis / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D015997:Neonatal Screening / Q000379:methods*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D013542:Sweat / Q000737:chemistry*; D013997:Time Factors
chemical_list: D002712:Chlorides