Increased diagnostic value of LCI in pulmonary exacerbations in cystic fibrosis paediatric patients using the corrected Exhalyzer software.

Abstract

Multiple breath washout (MBW) technique has been widely used in cystic fibrosis (CF) patients for several years. Unfortunately the most commonly used device, the Exhalyzer, overestimated the lung clearance index (LCI) results due to the software error. The aim of the study was to compare the predictive value of LCI in the CF pulmonary exacerbations (PE) calculated with the updated and the previously used softwares. <b>Materials and methods:</b> We compared the predictive values of LCI obtained with the 3.2.1 and 3.3.1 Spiroware software. The measurements were performed during 259 visits (stable and exacerbations) in 47 CF paediatric patients For the analysis, we used 39 ΔPE pairs (PE preceded by stable visit) and 138 ΔS pairs (stable visit preceded by the stable visit) to compare the LCI changes during PE. The areas under the Receiver Operating Curves and odds ratios were calculated based on the differences between ΔPEs and ΔSs. The exacerbation risk was estimated using a logistic regression model with generalised estimating equations (GEE). Statistical analysis was performed with StataV16 software. <b>Results:</b> The predictive value (AUCROC) of changes between the two consecutive visits for LCI increased from 0.64 to 0.67 using the 3.3.1 Spiroware software. The cut-off value of the difference indicating the increased risk for PE decreased from 2.06 (OR 4.38; 95% CI 2.01-9.55) to 1.6 (OR 4.77; 95% CI 2.26-10.06). <b>Conclusions:</b> Using the recalculated LCI values might increase the diagnostic value of this parameter in PE in CF paediatric patients. The study was supported by the Polish National Science Centre, grant no. 2016/22/E/NZ5/00383