Real-world clinical examples that could result from the findings of this review

Clinical scenarioImplications
A patient completes baseline FEV1 spirometry supervised in clinic and subsequently completes spirometry unsupervised at home and obtains the same results.The results from this systematic review indicate that, based on the CI and LoA for FEV1, a clinician cannot be confident that the results were truly the same. Despite there being no apparent change in their underlying lung function, there is the chance of a mean underestimation of 106 mL with home spirometry and a 39% chance that the difference would be >200 mL from the supervised clinic FEV1 measurement.
A patient who feels unwell at home records a remote FEV1 spirometry measurement that is >10% lower than a previous supervised clinic measurement, a change frequently used as an indicator for bronchiectasis exacerbations.As described in the example above, this difference could be due to chance or could indicate a true decline in lung function. Crucially, if the home and clinic results appeared the same then important changes in the patient's health could be missed, due to false reassurance to the patient and clinician.

FEV1: forced expiratory volume in 1 s; LoA: limit of agreement; CI: confidence interval.