title: Association of sweat chloride concentration at time of diagnosis and CFTR genotype with mortality and cystic fibrosis phenotype.
abstract: BACKGROUND
  The extent to which sweat chloride concentration predicts survival and clinical phenotype independently of CFTR genotype in cystic fibrosis is not well understood.
  
  
  METHODS
  We analyzed the US Cystic Fibrosis Foundation Patient Registry data using Cox regression to examine the relationship between sweat chloride concentration (<60, 60-<80, ≥80mmol/L), CFTR genotype (high and lower risk for lung function decline), and survival and mixed linear regression to examine the relationship between sweat chloride, CFTR genotype, and measures of lung function and growth.
  
  
  RESULTS
  When included in the same model, CFTR genotype, but not sweat chloride, was independently associated with survival and with lung function, height, and BMI. Among patients with unclassified CFTR genotype, sweat chloride was an independent predictor of survival (<60 HR 0.53 [0.37, 0.77], 60-<80 0.51 [0.42, 0.63]).
  
  
  CONCLUSIONS
  Sweat chloride concentration may be a useful predictor of mortality and clinical phenotype when CFTR genotype functional class is unclassified.
authors: National Referral Center for Adult Cystic Fibrosis, St. Vincent's University Hospital, Dublin, Ireland. Electronic address: e.mckone@st-vincents.ie.
authors: Edward F
authors: EF
authors: McKone
authors: Scientific Affairs, Quintiles Real World Late Phase Research, Cambridge, MA, USA.
authors: Priscilla
authors: P
authors: Velentgas
authors: Scientific Affairs, Quintiles Real World Late Phase Research, Cambridge, MA, USA.
authors: Anna J
authors: AJ
authors: Swenson
authors: Division of Pulmonary and Critical Care Medicine, University of Washington, Seattle, WA, USA.
authors: Christopher H
authors: CH
authors: Goss
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D002712:Chlorides / Q000378:metabolism*; D003550:Cystic Fibrosis / Q000175:diagnosis* / Q000235:genetics / Q000401:mortality; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics*; D005260:Female; D005500:Follow-Up Studies; D005838:Genotype; D006801:Humans; D008297:Male; D009154:Mutation; D010641:Phenotype; D011379:Prognosis; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D015996:Survival Rate / Q000639:trends; D013542:Sweat / Q000737:chemistry*; D014481:United States / Q000453:epidemiology
chemical_list: D002712:Chlorides; D019005:Cystic Fibrosis Transmembrane Conductance Regulator
keywords: Cystic fibrosis; Genetics; Respiratory function; Survival analysis