Longitudinal association between lung function and health-related quality of life in cystic fibrosis

Thorax. 2013 Feb;68(2):149-54. doi: 10.1136/thoraxjnl-2012-202552. Epub 2012 Nov 9.


Background: Lung function is an important indicator of cystic fibrosis disease status and those with better forced expiratory volume in 1 s (FEV(1))% predicted have tended to report a better health-related quality of life (HRQoL) in cross-sectional studies. The relationship between lung function and HRQoL over time is unknown. This work assesses the natural progression of HRQoL reporting over many years and compares assessments across a whole decade and evaluates the relationship between lung function and HRQoL longitudinally.

Methods: Demographic (age, gender), clinical (FEV(1)% predicted, body mass index, diabetes, Burkholderia cepacia complex, intravenous access device and nutritional status) and HRQoL (Cystic Fibrosis Quality of Life Questionnaire) variables were obtained every 2 years over a 12-year period (seven time points from 1998 to 2010).

Results: HRQoL and lung function declined slowly over time and significant decade changes were observed for FEV(1)% predicted and the nine domains of the Cystic Fibrosis Quality of Life Questionnaire. The results of random coefficient modelling indicated that, at the population level, decreasing FEV(1)% predicted was associated with decreasing HRQoL after adjusting for confounding variables. However, the percentage of patients for whom a decrease in lung function was associated with a decrease in HRQoL differed according to the quality of life domain.

Conclusions: HRQoL and FEV(1)% predicted decline slowly; nevertheless, a decrease in lung function predicted a decrease in HRQoL over time.

MeSH terms

  • Adolescent
  • Adult
  • Cystic Fibrosis / physiopathology*
  • Female
  • Forced Expiratory Volume
  • Health Status
  • Humans
  • Male
  • Middle Aged
  • Prospective Studies
  • Quality of Life*
  • Young Adult