title: Year-to-year changes in lung function in individuals with cystic fibrosis.
abstract: BACKGROUND
  We examined the year-to-year change in FEV(1) for individuals and the overall cystic fibrosis population to better understand how individual trends may differ from population trends.
  
  
  METHODS
  We calculated individual yearly changes using the largest annual FEV(1) percent predicted (FEV(1)%) measurement in 20,644 patients (6-45years old) included in the Epidemiologic Study of Cystic Fibrosis. We calculated yearly population changes using age-specific medians.
  
  
  RESULTS
  FEV(1)% predicted decreased 1-3 points per year for individuals, with maximal decreases in 14-15year olds. Population changes agreed with individual changes up to age 15; however after age 30, yearly population change approximated zero while individual FEV(1)% predicted decreases were 1-2 points per year.
  
  
  CONCLUSIONS
  Adolescents have the greatest FEV(1)% predicted decreases; however, loss of FEV(1) is a persistent risk in 6-45year old CF patients. Recognizing individual year-to-year changes may improve patient-specific care and may suggest new methods for measuring program quality.
authors.affiliation: University of Utah, 26 North 1900 East, Salt Lake City, UT 84132-4701,USA. ted.liou@utah.edu
authors.forename: Theodore G
authors.initials: TG
authors.lastname: Liou
authors.forename: Eric P
authors.initials: EP
authors.lastname: Elkin
authors.forename: David J
authors.initials: DJ
authors.lastname: Pasta
authors.forename: Joan R
authors.initials: JR
authors.lastname: Jacobs
authors.forename: Michael W
authors.initials: MW
authors.lastname: Konstan
authors.forename: Wayne J
authors.initials: WJ
authors.lastname: Morgan
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Wagener
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002648:Child; D003550:Cystic Fibrosis / Q000503:physiopathology*; D018450:Disease Progression; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D055815:Young Adult
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