Table 5

Estimates for clinically relevant thresholds for improvement and deterioration on the CCQ

CCQ	T3–T0		T6–T0		T12–T0		Weighted threshold
Change	Improvement	Deterioration	Improvement	Deterioration	Improvement	Deterioration	Improvement	Deterioration
Minimal change
Anchor-based PR (n)	107	36	96	42	88	43	291	121
Anchor-based PR	−0.44	0.42	−0.42	0.48	−0.50	0.66	−0.45	0.53
Anchor-based RCP (n)	12	27	14	36	18	46	32	82
Anchor-based RCP	–	–	−0.44	0.46	−0.38	0.33	−0.41	0.39
Distribution-based PR (n)	225	130	181	138	180	129	586	397
Distribution-based PR	−0.36	0.34	−0.34	0.34	−0.36	0.31	−0.35	0.33
Distribution-based RCP (n)	96	89	87	80	77	88	260	257
Distribution-based RCP	−0.19	0.19	−0.26	0.23	−0.27	0.20	−0.24	0.21
Moderate change
Anchor-based PR (n)	51	9	45	7	37	10	133	7
Anchor-based PR	−0.86	–	−0.72	1.23	−0.90	–	−0.82	1.23
Anchor-based RCP (n)	5	8	12	9	5	9	–	17
Anchor-based RCP	–	0.85	–	–	–	0.42	–	0.62
Large change
Anchor-based PR (n)	16	3	12	2	14	3	42	–
Anchor-based PR	−0.96	–	−1.03	–	−1.18	–	−1.05	–
Anchor-based RCP (n)	4	3	0	2	9	4	9	4
Anchor-based RCP	–	–	–	–	−1.12	0.98	−1.12	0.98
No change
Anchor-based PR (n)	133		115		114		362
Anchor-based PR	−0.07		0.17		0.10		0.06
Anchor-based RCP (n)	141		113		83		337
Anchor-based RCP	−0.03		−0.10		−0.04		−0.06

Data reported as clinically relevant threshold or n. Negative change represents improvement for all health status instruments. Paired t-tests were applied with significance level at p<0.05. Non-significant results were excluded, except for the ‘No change’ group.
CCQ, Clinical COPD Questionnaire; n, number of patients; PR, pulmonary rehabilitation; RCP, routine clinical practice; T0, baseline measurement; T3, 3-month follow-up; T6, 6-month follow-up; T12, 12-month follow-up.