Table 3. MCID patient-referencing results.

Instrument	No/hardly any improvement (GRC −1, 0 or +1) N=98		Minimal improvement (GRC +2 or +3) N=196		Moderate improvement (GRC +4 or +5) N=123		Major improvement (GRC +6 or +7) N=25
	Δa	95% CIb	Δa	95% CIb	Δa	95% CIb	Δa	95% CIb
CCQ
Symptoms	−0.32	−0.54 to −0.10	−0.55	−0.70 to −0.40	−0.76	−0.96 to −0.56	−1.48	−1.97 to −0.99
Functional	−0.27	−0.47 to −0.07	−0.55	−0.68 to −0.43	−0.78	−0.98 to −0.58	−0.97	−1.31 to −0.63
Mental	−0.53	−0.84 to −0.22	−0.58	−0.78 to −0.38	−0.67	−0.94 to −0.39	−1.34	−1.84 to −0.84
Total	−0.34	−0.52 to −0.15	−0.56	−0.68 to −0.44	−0.75	−0.92 to −0.58	−1.25	−1.54 to −0.96
CAT
Total	−2.05	−3.13 to −0.98	−3.12	−3.86 to −2.37	−3.67	−4.70 to −2.67	−6.44	−8.99 to −3.89
SGRQ
Symptoms	−7.03	−10.86 to −3.19	−13.12	−16.05 to −10.19	−19.91	−23.92 to −15.90	−30.62	−38.40 to −22.84
Activities	−3.03	−5.28 to −0.78	−5.9	−7.88 to −4.08	−10.33	−12.78 to −7.87	−12.66	−18.69 to −6.62
Impact	−6.72	−9.57 to −3.86	−8.24	−10.14 to −6.33	−10.32	−12.77 to −7.87	−17.90	−23.64 to −12.16
Total	−5.57	−7.79 to −3.35	−8.40	−10.07 to −6.73	−11.83	−14.00 to −9.66	−18.50	−22.81 to −14.18

Abbreviations: CAT, COPD assessment test; CCQ, Clinical COPD Questionnaire; CI, confidence interval; GRC, global rating of change; MCID, minimal clinically important difference; SGRQ, St. George’s Respiratory Questionnaire; Δ, change score; 95% CI, 95% confidence interval.

^aData were reported as mean change scores. Negative change represents improvement for all instruments.

^bPaired t-tests were applied to normally distributed variables, and Wilcoxon signed-rank tests were used for not normally distributed data. Data were reported as 95% CI. All change scores were significant with P-value <0.05.