Figure 3.

Difference in ΔLzapp% between patients with a minimal clinically significant difference for CAT after PR.

Notes: Box plots illustrating the change (%) of Lzapp at FRC between patients “slightly improved” (who achieved a <2 points reduction of CAT score) or “markedly improved” (who achieved ≥2 points reduction in CAT score), *P<0.05 (Mann–Whitney U-test). The red line represents the ΔLzapp% cutoff value determined by the receiver operating characteristic (ROC) curve analysis showed in Figure 5.

Abbreviations: Lzapp, length of diaphragm zone of apposition; FRC, functional residual capacity; CAT, COPD Assessment Test; PR, pulmonary rehabilitation.