Improved survival at low lung function in cystic fibrosis: cohort study from 1990 to 2007

Objectives To evaluate the survival of patients with cystic fibrosis whose lung function has deteriorated to a forced expiratory volume in one second (FEV(1)) below 30% predicted in the recent treatment era and to explore factors associated with any change in survival. Design Cohort study. Setting Adult cystic fibrosis unit in London. Participants 276 patients (147 (53%) male) whose FEV(1) was first observed to be less than 30% predicted between 1 January 1990 and 31 December 2003. Main outcome measure Survival during follow-up to 31 December 2007 in two year sub-cohorts. Results Median survival improved from 1.2 years in the 1990-1 group to 5.3 years in the 2002-3 group, with a marked improvement in survival from 1994. The use of nebulised recombinant human DNase was significantly associated with a reduced risk of death (hazard ratio 0.59, 95% confidence interval 0.44 to 0.79). Significantly increased risks were associated with a body mass index under 19 (hazard ratio 1.52, 1.10 to 2.10), long term oxygen therapy (3.52, 2.49 to 4.99), and nebulised antibiotics (1.84, 1.05 to 3.22). Conclusion A marked improvement has occurred in the survival of patients with cystic fibrosis with an FEV(1) less than 30% predicted. Secondary analyses suggest that some of this improvement may be due to use of recombinant human DNase.