Abstract
Background: The recently described sensor-crosstalk error in the
multiple-breath washout (MBW) device (Exhalyzer D, Eco Medics AG,
Duernten, Switzerland) could highly influence clinimetric properties and
the current interpretation of MBW results. This study reanalyzes MBW
data from clinical routine in the corrected software version Spiroware®
3.3.1 and evaluates the effect on outcomes. Methods: We included
nitrogen-MBW data from healthy children and children with CF from
previously published trials and ongoing cohort studies. We specifically
compared LCI analyzed in Spiroware 3.2.1 and 3.3.1 with regards to i)
feasibility, ii) repeatability and iii) validity as outcome parameters
in children with CF. Results: (i) All previously collected measurements
could be reanalyzed and resulted in unchanged feasibility in Spiroware
3.3.1. (ii) Short- and midterm repeatability of LCI was similar in both
software versions. (iii) Clinical validity of LCI remained similar in
Spiroware 3.3.1, however, resulted in lower values. Discrimination
between health and disease was comparable between both software
versions. The increase in LCI over time was less pronounced with 0.16
LCI units/year (95% CI 0.08; 0.24) vs. 0.30 LCI units/year (95% CI
0.21; 0.38) in 3.2.1. Response to intervention in children receiving
CFTR-modulator therapy resulted in a comparable improvement in LCI in
both Spiroware versions. Conclusion: Our study confirms that clinimetric
properties of LCI remain unaffected after correction for the
cross-sensitivity error in Spiroware software.