title: Predicting survival in end-stage cystic fibrosis.
abstract: The natural history of cystic fibrosis (CF) is unpredictable and the optimal timing for lung transplantation in end-stage disease uncertain. Predicting survival based on FEV1 alone remains controversial and therefore the aim of this study was to assess the value of walk test performance in pre-transplant assessment. Retrospective review of adult patients with end-stage CF who underwent transplant assessment between 1988 and 2004 including a documented walk test on room air, but who died before transplant. The six-minute walk test (6MWT) was used between 1988 and 1993 and the shuttle walk test (SWT) thereafter, the two cohorts were therefore individually assessed. A total of 121 patients were identified. The median (IQR) survival in patients performing SWT (n=77) and 6MWT (n=44) was 363 days (226, 566) and 433 days (232, 844), respectively, with survival in both cohorts significantly associated with pre-test (resting) heart rate (HR) (p<0.03), but not distance walked, pre-test SpO2, FEV1 or BMI. It was predicted that 85% of patients performing SWT with a resting HR of 120 bpm, 70% of those with a HR of 109 bpm (cohort median) but only 25% with a HR of 72 bpm would die within 500 days. Distance walked in the SWT was significantly related to pre-test HR (p<0.01), SpO2 (p<0.01) and Borg score (p=0.016) when performing linear regression. Only pre-test HR remained significant when performing multiple regression. Resting heart rate was the only consistent parameter in this study at predicting a high risk of dying on the transplant waiting list.
authors.affiliation: Department of Cystic Fibrosis, Royal Brompton and Harefield NHS Foundation Trust, Sydney Street, London SW3 6NP, UK. ian.ketchell@cardiffandvale.wales.nhs.uk
authors.forename: Robert I
authors.initials: RI
authors.lastname: Ketchell
authors.forename: Michael
authors.initials: M
authors.lastname: Roughton
authors.forename: Penny
authors.initials: P
authors.lastname: Agent
authors.forename: Khin
authors.initials: K
authors.lastname: Gyi
authors.forename: Margaret E
authors.initials: ME
authors.lastname: Hodson
mesh_terms: D000328:Adult; D003550:Cystic Fibrosis / Q000401:mortality* / Q000503:physiopathology / Q000601:surgery; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D016040:Lung Transplantation / Q000401:mortality* / Q000502:physiology; D008297:Male; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies; D013147:Spirometry; D016019:Survival Analysis; D016138:Walking / Q000502:physiology*; D055815:Young Adult