Svedberg M, et al. – Researchers undertook this investigation to assess Lung Clearance Index (LCI) variability in clinically stable Cystic Fibrosis (CF) lung disease in school age children. They observed that LCI within–subject variability was low and comparable to FEV₁% pred. which strengthen the use of LCI to monitor lung disease progression in CF patients. They suggested that an increase in LCI >17% compared to the previous LCI–measurement in clinically stable CF patients may, therefore, show early lung disease progression.

Methods

• Participants were paediatric patients, aged 6 to 17 years, attending the outpatient CF clinic performed Multiple Breath Nitrogen Washout (Exhalyzer D) and spirometry every third month over a period of 1 year.
• Clinical stability was evaluated by the Cystic Fibrosis Clinical Score (CFCS) at each visit.

Results

• 25 children were selected: baseline median (range) FEV₁% pred. 91 (55–122)%, LCI 9.1 (6.4–18.6), CFCS 15 (12-23).
• An aggregate of one hundred seven visits were incorporated into the examination, of which 93% were characterized as clinically stable.
• In clinically stable visits, within-subject variability of LCI and FEV₁% pred. were 10% and 16%, respectively.
• It was observed in the findings that the upper limit of normal (ULN, 95% percentile) of LCI variability during clinical stability was 17%.