Table 2 Can spirometry performed at home be used as an outcome measure in cystic fibrosis trials?

Spirometry is a key assessment parameter in CF and is often a primary outcome in clinical trials. Patients require training to perform this maneuver, and normally, clinical trial staff oversee the test to ensure that the procedure is performed correctly—this is important to ensure the robustness of the results. With recent technological advances, compact home spirometry equipment is now available, but is not yet implemented as a standard in routine CF care. In addition, these devices have not yet been validated for the assessment of spirometry endpoints for clinical trials. In face-to-face spirometry assessments, patients are coached by the research nurse or coordinator regarding the necessary technique required to perform a “valid” forced expiratory maneuver. Spirometry performed at home, even when utilizing remote coaching via video-link, may therefore be qualitatively suboptimal as compared to an in-clinic assessment. This could lead to variable results, especially if some assessments are performed at home and others in the clinic. A study sponsored by the Cystic Fibrosis Foundation is investigating how home spirometry results can be “corrected” in order to be comparable to spirometry performed in clinics [12]. It is unknown at this point how regulators will evaluate the results of key outcome parameters obtained with unvalidated home equipment and this is an area requiring further research.