title: Loss of fat-free mass over four years in adult cystic fibrosis is associated with high serum interleukin-6 levels but not tumour necrosis factor-alpha.
abstract: OBJECTIVE
  Malnutrition is associated with poorer outcome in cystic fibrosis (CF). This follow-up study aimed to document nutritional status changes, including fat-free mass (FFM), in adults with CF; and to identify predictors of FFM loss.
  
  
  METHODS
  Fifty-eight non-transplanted CF adults (mean ± SD forced expiratory volume in one second (FEV1) 63.7 ± 21.4%predicted; mean ± SD age 30.3 ± 7.7years at baseline) were studied at baseline and 3.6 ± 0.4 years later. Body composition was measured using dual-energy X-ray absorptiometry. At follow-up, blood was analysed for interleukin-6 and tumour necrosis factor-α (TNF-α) on three occasions over six months and averaged for each participant. Associations with annual percentage change in FFM (ann%ΔFFM), including cytokines, CF genotype and annual change in FEV1%predicted (annΔFEV1%), were determined.
  
  
  RESULTS
  Mean FFM was 49.5 ± 8.8 kg at baseline and 49.6 ± 8.9 kg at follow-up (p = 0.66). Ann%ΔFFM ranged from -2.0 to +3.6%. FEV1%predicted declined by 1.2 ± 2.4% per year. Forty percent of participants had elevated average interleukin-6 levels. Ann%ΔFFM was negatively correlated with interleukin-6 levels (rho -0.34, p = 0.008), but not TNF-α or annΔFEV1%. F508DEL homozygote or heterozygote participants had greater FFM loss than those carrying no F508DEL allele (p = 0.01).
  
  
  CONCLUSIONS
  Higher serum interleukin-6 and presence of the F508DEL mutation, but not TNF-α, were associated with FFM loss in adults with CF.
authors.affiliation: Nutrition Department, Alfred Hospital, Commercial Road, Melbourne, Victoria 3004, Australia; Department of Medicine, Monash University, Alfred Hospital, Commercial Road, Melbourne, Victoria 3004, Australia; Department of Dietetics and Human Nutrition, La Trobe University, Bundoora, Victoria 3086, Australia. Electronic address: s.king@alfred.org.au.
authors.forename: Susannah J
authors.initials: SJ
authors.lastname: King
authors.affiliation: Nutrition Department, Alfred Hospital, Commercial Road, Melbourne, Victoria 3004, Australia; Department of Medicine, Monash University, Alfred Hospital, Commercial Road, Melbourne, Victoria 3004, Australia. Electronic address: i.nyulasi@alfred.org.au.
authors.forename: Ibolya B
authors.initials: IB
authors.lastname: Nyulasi
authors.affiliation: Department of Epidemiology and Preventive Medicine, Monash University, Commercial Road, Melbourne, Victoria 3004, Australia. Electronic address: Michael.bailey@monash.edu.
authors.forename: Michael
authors.initials: M
authors.lastname: Bailey
authors.affiliation: Department of Medicine, Monash University, Alfred Hospital, Commercial Road, Melbourne, Victoria 3004, Australia; Department of Allergy, Immunology and Respiratory Medicine, Alfred Hospital, Commercial Road, Melbourne, Victoria 3004, Australia. Electronic address: t.kotsimbos@alfred.org.au.
authors.forename: Tom
authors.initials: T
authors.lastname: Kotsimbos
authors.affiliation: Department of Medicine, Monash University, Alfred Hospital, Commercial Road, Melbourne, Victoria 3004, Australia; Department of Allergy, Immunology and Respiratory Medicine, Alfred Hospital, Commercial Road, Melbourne, Victoria 3004, Australia. Electronic address: john.wilson@monash.edu.
authors.forename: John W
authors.initials: JW
authors.lastname: Wilson
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D001823:Body Composition; D003550:Cystic Fibrosis / Q000097:blood* / Q000150:complications; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D044342:Malnutrition / Q000097:blood* / Q000150:complications; D009043:Motor Activity; D009752:Nutritional Status; D011446:Prospective Studies; D014409:Tumor Necrosis Factor-alpha / Q000097:blood*; D055815:Young Adult
chemical_list: D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha
keywords: Body composition; Cystic fibrosis; Fat-free mass; Interleukin-6; Nutritional status