title: Reference percentiles for FEV(1) and BMI in European children and adults with cystic fibrosis.
abstract: BACKGROUND
  The clinical course of Cystic Fibrosis (CF) is usually measured using the percent predicted FEV(1) and BMI Z-score referenced against a healthy population, since achieving normality is the ultimate goal of CF care. Referencing against age and sex matched CF peers may provide valuable information for patients and for comparison between CF centers or populations. Here, we used a large database of European CF patients to compute CF specific reference equations for FEV(1) and BMI, derived CF-specific percentile charts and compared these European data to their nearest international equivalents.
  
  
  METHODS
  34859 FEV(1) and 40947 BMI observations were used to compute European CF specific percentiles. Quantile regression was applied to raw measurements as a function of sex, age and height. Results were compared with the North American equivalent for FEV(1) and with the WHO 2007 normative values for BMI.
  
  
  RESULTS
  FEV(1) and BMI percentiles illustrated the large variability between CF patients receiving the best current care. The European CF specific percentiles for FEV(1) were significantly different from those in the USA from an earlier era, with higher lung function in Europe. The CF specific percentiles for BMI declined relative to the WHO standard in older children. Lung function and BMI were similar in the two largest contributing European Countries (France and Germany).
  
  
  CONCLUSIONS
  The CF specific percentile approach applied to FEV(1) and BMI allows referencing patients with respect to their peers. These data allow peer to peer and population comparisons in CF patients.
authors.affiliation: AP-HP, Hôpital Trousseau-Pediatric Pulmonary Department, Hopital St Antoine-Public Health Department, Paris, France.
authors.forename: Pierre-Yves
authors.initials: PY
authors.lastname: Boëlle
authors.forename: Laura
authors.initials: L
authors.lastname: Viviani
authors.forename: Pierre-Francois
authors.initials: PF
authors.lastname: Busson
authors.forename: Hanne V
authors.initials: HV
authors.lastname: Olesen
authors.forename: Sophie
authors.initials: S
authors.lastname: Ravilly
authors.forename: Martin
authors.initials: M
authors.lastname: Stern
authors.forename: Baroukh M
authors.initials: BM
authors.lastname: Assael
authors.forename: Celeste
authors.initials: C
authors.lastname: Barreto
authors.forename: Pavel
authors.initials: P
authors.lastname: Drevinek
authors.forename: Muriel
authors.initials: M
authors.lastname: Thomas
authors.forename: Uros
authors.initials: U
authors.lastname: Krivec
authors.forename: Meir
authors.initials: M
authors.lastname: Mei-Zahav
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Vibert
authors.forename: Annick
authors.initials: A
authors.lastname: Clement
authors.forename: Anil
authors.initials: A
authors.lastname: Mehta
authors.forename: Harriet
authors.initials: H
authors.lastname: Corvol
mesh_terms: D000293:Adolescent; D000328:Adult; D015992:Body Mass Index; D002648:Child; D003550:Cystic Fibrosis / Q000503:physiopathology*; D005060:Europe; D005541:Forced Expiratory Volume; D006801:Humans; D012016:Reference Values; D055815:Young Adult