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Cystic fibrosis: bench to bedside
S44 Lung clearance index (LCI) and FEV1 correlate equally with treatment burden as measured by cystic fibrosis questionnaire-revised (CFQ-R)
  1. K O'Neill1,
  2. J M Bradley2,
  3. M Tunney3,
  4. J S Elborn1
  1. 1Centre for Infection and Immunity, Queen's University Belfast, Belfast, UK
  2. 2Health and Rehabilitation Sciences Research Institute, University of Ulster, UK
  3. 3School of Pharmacy, Queen's University Belfast, Belfast, UK

Abstract

Introduction LCI derived from multiple breath washout (MBW), measures the elimination of an inert marker gas during tidal breathing and is a sensitive measure of ventilation inhomogeneity in CF. LCI is more sensitive than FEV1 and FEF25−75 in detecting airways abnormalities and does not require a forced manoeuvre. The CFQ-R is a validated patient reported outcome used to assess health related quality of life (HRQoL) and patient perception of symptoms. There is a need to better understand the relationship between LCI, HRQoL and symptoms.

Objective To investigate the relationship between LCI, FEV1 % pred, HRQoL and symptoms as measured by the CFQ-R.

Methods These data are part of a larger study investigating the role of LCI as a tool to monitor lung function longitudinally. Patients were recruited from the adult and paediatric CF centres in Belfast Health and Social Care Trust. Inclusion criteria: clinical diagnosis of CF; clinically stable (exacerbation free=4 weeks); informed consent. Age appropriate versions of the CFQ-R were used (patients >14 years, children aged 12 and 13, children aged 6–11). A parent questionnaire was completed in addition where appropriate (for children aged 6–13). The instrument yielded a score of 0–100 for each domain, with higher numbers indicating better function on various domains. Participants completed three MBW tests, using 0.2% sulphur hexafluoride and a modified Innocor device. LCI was reported as the mean of at least 2 acceptable tests. Spirometry was performed to ATS/ERS standards.

Results Data were collected for 21 patients (15M:6F), age range 6–51 yrs, mean (SD) 26.4 (13.7). Mean (SD) FEV1 % pred was 77.1 (16.3). Mean (SD) LCI was 9.4 (2.5) (normal <7.5). LCI correlated negatively with FEV1% pred (r=−0.62 p=0.003). The domain of treatment burden was significantly correlated with LCI (r=−0.67 p=0.001) and FEV1% pred (r=0.69 p=0.001). However no correlation was observed with respiratory symptoms or any other domain of the CFQ-R.

Conclusion Patients with a greater treatment burden are more likely to have more severe lung disease. The severity of CF lung disease as determined by FEV1% pred and LCI correlate equally with treatment burden. This further validates LCI as a useful measure of lung function.

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