title: Quality of life is associated with physical activity and fitness in cystic fibrosis.
abstract: BACKGROUND
  Health-related and disease-specific quality of life (HRQoL) has been increasingly valued as relevant clinical parameter in cystic fibrosis (CF) clinical care and clinical trials. HRQoL measures should assess - among other domains - daily functioning from a patient's perspective. However, validation studies for the most frequently used HRQoL questionnaire in CF, the Cystic Fibrosis Questionnaire (CFQ), have not included measures of physical activity or fitness. The objective of this study was, therefore, to determine the cross-sectional and longitudinal relationships between HRQoL, physical activity and fitness in patients with CF.
  
  
  METHODS
  Baseline (n = 76) and 6-month follow-up data (n = 70) from patients with CF (age ≥12 years, FEV1 ≥35%) were analysed. Patients participated in two multi-centre exercise intervention studies with identical assessment methodology. Outcome variables included HRQoL (German revised multi-dimensional disease-specific CFQ (CFQ-R)), body composition, pulmonary function, physical activity, short-term muscle power, and aerobic fitness by peak oxygen uptake and aerobic power.
  
  
  RESULTS
  Peak oxygen uptake was positively related to 7 of 13 HRQoL scales cross-sectionally (r = 0.30-0.46). Muscle power (r = 0.25-0.32) and peak aerobic power (r = 0.24-0.35) were positively related to 4 scales each, and reported physical activity to 1 scale (r = 0.29). Changes in HRQoL-scores were directly and significantly related to changes in reported activity (r = 0.35-0.39), peak aerobic power (r = 0.31-0.34), and peak oxygen uptake (r = 0.26-0.37) in 3 scales each. Established associates of HRQoL such as FEV1 or body mass index correlated positively with fewer scales (all 0.24 < r < 0.55).
  
  
  CONCLUSIONS
  HRQoL was associated with physical fitness, especially aerobic fitness, and to a lesser extent with reported physical activity. These findings underline the importance of physical fitness for HRQoL in CF and provide an additional rationale for exercise testing in this population.
  
  
  BACKGROUND
  ClinicalTrials.gov, NCT00231686.
authors.affiliation: Pediatric Department, University of Würzburg, Würzburg, Germany. hebestreit@uni-wuerzburg.de.
authors.forename: Helge
authors.initials: H
authors.lastname: Hebestreit
authors.forename: Kerstin
authors.initials: K
authors.lastname: Schmid
authors.forename: Stephanie
authors.initials: S
authors.lastname: Kieser
authors.forename: Sibylle
authors.initials: S
authors.lastname: Junge
authors.forename: Manfred
authors.initials: M
authors.lastname: Ballmann
authors.forename: Kristina
authors.initials: K
authors.lastname: Roth
authors.forename: Alexandra
authors.initials: A
authors.lastname: Hebestreit
authors.forename: Thomas
authors.initials: T
authors.lastname: Schenk
authors.forename: Christian
authors.initials: C
authors.lastname: Schindler
authors.forename: Hans-Georg
authors.initials: HG
authors.lastname: Posselt
authors.forename: Susi
authors.initials: S
authors.lastname: Kriemler
mesh_terms: D003430:Cross-Sectional Studies; D003550:Cystic Fibrosis / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009043:Motor Activity; D010809:Physical Fitness; D011788:Quality of Life; D011795:Surveys and Questionnaires; D055815:Young Adult