Fig. 3
Improvement in SAC-TDI focal score at Week 24. Vertical dotted lines indicate quintiles of reversibility at baseline. The MCID of SAC-TDI score is ≥ 1-point improvement from baseline [13]. BDI, Baseline Dyspnoea Index; CI, confidence interval; FEV1, forced expiratory volume in 1 s; FP, fractional polynomial; LS, least squares; MCID, minimal clinically important difference; SAC-TDI, self-administered computerised-Transition Dyspnoea Index; SAL, salmeterol; UMEC, umeclidinium; VI, vilanterol