title: Evidence for decline in the incidence of cystic fibrosis: a 35-year observational study in Brittany, France.
abstract: BACKGROUND
  Cystic fibrosis (CF) is an autosomal recessive disorder whose incidence has long been estimated as 1/2500 live births in Caucasians. Expanding implementation of newborn screening (NBS) programs now allows a better monitoring of the disease incidence, what is essential to make reliable predictions for disease management. This study assessed time trends in the birth incidence of CF over a long period (35 years: 1975-2009) in an area where CF is frequent (Brittany, France) and where NBS has been implemented for more than 20 years.
  
  
  METHODS
  This study enrolled CF patients born in Brittany between January 1st 1975 and December 31st 2009 (n = 483). Time trends in incidence were examined using Poisson regression and mainly expressed using the average percent change (APC).
  
  
  RESULTS
  The average number of patients born each year declined from 18.6 in the late 1970's (period 1975-79) to 11.6 nowadays (period 2005-09). The corresponding incidence rates dropped from 1/1983 to 1/3268, which represented a decline close to 40% between these two periods (APC = -39.3%, 95% CI = -55.8% to -16.7%, p = 0.0020). A clear breakpoint in incidence rate was observed at the end of the 1980's (p < 0.0001). However, the incidence rate has remained quite stable since that time (annual APC = -1.0%, 95% CI = -3.0% to 1.1%, p = 0.3516).
  
  
  CONCLUSIONS
  This study provides an accurate picture of the evolution of the incidence of a genetic disease over a long period and highlights how it is influenced by the health policies implemented. We observed a 40% drop in incidence in our area which seems consecutive to the availability of prenatal diagnosis.
authors.affiliation: Inserm, U1078, Brest, F-29200, France. virginie.scotet@inserm.fr
authors.forename: Virginie
authors.initials: V
authors.lastname: Scotet
authors.forename: Ingrid
authors.initials: I
authors.lastname: Duguépéroux
authors.forename: Philippe
authors.initials: P
authors.lastname: Saliou
authors.forename: Gilles
authors.initials: G
authors.lastname: Rault
authors.forename: Michel
authors.initials: M
authors.lastname: Roussey
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Audrézet
authors.forename: Claude
authors.initials: C
authors.lastname: Férec
mesh_terms: D003550:Cystic Fibrosis / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000453:epidemiology*; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D008297:Male; D015997:Neonatal Screening / Q000379:methods; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods; D013997:Time Factors; D016216:Ultrasonography, Prenatal