Fig. 2

Bland-Altman plot comparing hospital and home spirometry. The value for hospital FVC is the mean of the hospital-based FVC at baseline and after four weeks. The value for home spirometry is the mean of 28 home FVC readings. The solid line represents the mean difference and the dashed lines 95% limits of agreement (− 0.61 to 0.90 L).* This patient did not use the mouthpiece correctly leading to more variable and higher readings compared to hospital spirometry