Background

The lung clearance index (LCI), derived from the Multiple Breath Washout (MBW) test, is sensitive to treatment effects and compared with spirometry has higher feasibility in younger children and requires smaller sample sizes. As a result, the LCI has been endorsed by the European CF Society Clinical Trials Network for use as a primary outcome measure in CF clinical trials.
Methods

Here we describe the implementation of standardised protocols for MBW test performance, data collection and quality control to successfully incorporate LCI as a novel outcome measure in a large multicentre phase III clinical trial.
Results

Three regional (North America (NA), Europe (EU), Australia (AUS)) central over-reading centres (CORC) were established to provide a collaborative platform for MBW training, certification and quality control of data.

One hundred and thirty-two naïve operators from 53 sites across NA, EU and AUS were successfully trained and certified to perform MBW testing. Incorporation of a re-screening opportunity in the study protocol resulted a final screening feasibility rate of 93%, success remained high throughout the study resulting in an overall feasibility of MBW study data of 88.1% (1107/1257). MBW test acceptability was similar between geographical regions: NA (88%), EU (89%) and AUS (89%).
Conclusion

With this approach we achieved high MBW test feasibility and sustained collection of good quality data, demonstrating the utility of LCI as an effective primary endpoint in the first international phase III clinical trial to report LCI as the primary outcome.