Table 2.

Distributions of the D-12, CAT and E-RS total scores

	D-12 score (0–36)					CAT score (0–40)					E-RS Total score (0–40)
	Mean	Median	SD	Max.	Floor effect (%)	Mean	Median	SD	Max.	Floor effect (%)	Mean	Median	SD	Max.	Floor effect (%)
All subjects	0.2	0.0	0.6	6.0	84.0	4.3	3.0	3.9	25.0	14.6	1.2	0.0	1.9	15.0	53.3
Healthy non-smoking subjects*†	0.2	0.0	0.5	6.0	86.5	3.6	3.0	3.3	24.0	15.9	0.9	0.0	1.6	10.0	62.5
COPD defined by fixed ratio	0.3	0.0	0.8	4.0	81.2	4.8	4.0	4.1	19.0	15.3	1.6	1.0	2.2	12.0	44.7
Non-COPD smokers	0.2	0.0	0.5	6.0	82.0	4.8	4.0	4.1	25.0	13.1	1.5	1.0	2.1	15.0	46.5
Non-COPD never smokers	0.2	0.0	0.5	6.0	86.7	3.6	3.0	3.4	24.0	16.3	0.9	0.0	1.6	12.0	62.7
COPD defined by LLN	0.5	0.0	1.0	4.0	73.5	6.2	6.0	4.8	19.0	14.7	1.8	1.5	2.1	9.0	38.2
Non-COPD smokers	0.2	0.0	0.5	6.0	82.2	4.8	4.0	4.1	25.0	13.0	1.5	1.0	2.1	15.0	46.6
Non-COPD never smokers	0.2	0.0	0.6	6.0	86.8	3.6	3.0	3.4	24.0	16.5	0.9	0.0	1.6	10.0	62.7

*FEV₁ of >85% predicted and FEV₁/FVC of >0.7.

†A smoking history of <1 pack-year. Numbers in parentheses indicate the theoretical score range, and higher scores indicate worse status.

CAT, COPD assessment test; COPD, chronic obstructive pulmonary disease; D-12, Dyspnoea-12; E-RS, evaluating respiratory symptoms in COPD; FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity; LLN, lower limit of normal.