title: From lip to lab: salty tasting skin is the main clue that raises clinical suspicion of cystic fibrosis in young infants.
abstract: OBJECTIVE
  This study developed a clinical decision rule (CDR) to rule in or rule out cystic fibrosis (CF) in the first weeks of life.
  
  
  METHODS
  We combined a two-step nonconcurrent birth cohort and a cross-sectional controlled study in which observers and mothers were blinded to confirmatory sweat test results. Neonates from uncomplicated pregnancies and deliveries, with two subsequent tests for immunoreactive trypsinogen (IRT) higher than 70 ng/mL, were eligible to take part.
  
  
  RESULTS
  We included 49 CF-affected and 177 CF-unaffected infants with an average age of 34 days. CF-affected infants demonstrated statistically significant differences in weight gain, stool frequency and salty tasting skin from birth. Multivariate analysis showed that the main predictors of CF were salty tasting skin (odds ratio 17.2) and weight gain of <10.5 g per day (odds ratio 4.6). Depending on the CDR score, we obtained the following results: sensitivity (42.9-61.2%), specificity (89.6-96.5%), positive (62.5-77.8%) and negative (85.6-89.1%) predictive value and positive (5.8-12.3) and negative (0.4-0.6) likelihood ratio.
  
  
  CONCLUSIONS
  The CDR could provide a reliable index of clinical suspicion and timely referral for sweat testing in settings without newborn screening programmes and may also be applied to false-negative individuals where such programmes already exist.
authors: Department of Pediatrics, Medical School, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil.
authors: Paulo
authors: P
authors: Camargos
authors: Daniela Lima
authors: DL
authors: Gomes
authors: Cristina Gonçalves
authors: CG
authors: Alvim
authors: Fabrício Silva
authors: FS
authors: Gomes
authors: Júnia Maria Drumond
authors: JM
authors: Cajazeiro
mesh_terms: D000328:Adult; D000066491:Clinical Decision-Making; D003550:Cystic Fibrosis / Q000175:diagnosis*; D016021:Epidemiologic Studies; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D015997:Neonatal Screening; D012867:Skin; D013542:Sweat / Q000737:chemistry*; D013649:Taste; D055815:Young Adult
keywords: Clinical decision rule; Cystic fibrosis; Newborn screening; Salty tasting skin