. 2016 Aug 1;11:1745–1756. doi: 10.2147/COPD.S111508

Table 3.

Characteristics of patients with COPD substratified by FEV₁ decline

Demographics for FEV₁ Decline Groups COPD
FEV₁ decline group	Group 1 n=93				Group 2 n=42				Group 3 n=59				Group 4 n=201				Across all groups	Statistic between groups 1 and 4
	No decline (decline of <−0.1% predicted per year)				Decline of −0.1 to <−0.5				Decline of −0.5 to <−1.0				Decline of at least −1.0				Across all groups	Statistic between groups 1 and 4

	N	%	Mean	SD	N	%	Mean	SD	N	%	Mean	SD	N	%	Mean	SD	P-value	P-value
Never smokers	19	20.4%			2	4.8%			9	15.3%			52	25.9%			0.013	0.311
Index patient	85	91.4%			40	95.2%			53	89.8%			175	87.1%			0.382	0.280
Female	43	46.2%			14	33.3%			20	33.9%			76	37.8%			0.337	0.171
Age	93		54.1	8.6	42		50.6	8.0	59		52.5	8.4	201		53.0	10.0	0.193	0.456
FEV₁ % predicted	93		50.5	24.8	42		41.5	17.2	59		47.8	19.1	201		58.3	20.8	<0.0001	<0.0001
FVC % predicted	93		107.1	24.1	42		98.1	18.4	59		104.0	20.6	201		114.5	21.6	<0.0001	0.004
FEV₁/FVC	93		37.7	13.8	42		34.3	11.6	59		36.9	12.1	201		41.2	12.1	0.001	0.017
DLco % predicted	61		61.3	19.7	20		57.1	20.5	37		62.6	17.9	132		61.8	17.3	0.722	0.788
Kco % predicted	92		64.6	19.2	42		62.4	19.0	59		66.2	19.1	201		61.2	16.8	0.265	0.203
RV % predicted	89		126.4	39.4	42		147.9	48.1	57		137.5	34.5	199		121.9	37.1	0.001	0.295
TLC % predicted	89		116.2	14.8	42		119.2	17.7	57		117.2	12.7	199		117.1	15.7	0.852	0.822
RV/TLC	89		37.2	8.8	42		40.3	10.1	57		38.8	7.1	199		34.7	8.4	<0.0001	0.010
FEV₁ slope mL/year	93		11.2	32.3	42		−22.4	10.6	59		−36.3	8.2	201		−86.2	54.7	N/A	N/A
FEV₁ % slope per year	93		0.9	1.2	42		−0.3	0.1	59		−0.8	0.1	201		−2.4	1.4	N/A	N/A
Kco % slope per year	89		−1.3	1.8	41		−1.2	1.5	58		−1.58	1.8	189		−1.5	2.2	0.709	0.730
Distribution within Kco decline groups
Kco Group 1	16	18.0%			10	24.4%			8	13.8%			38	20.1%			0.633	0.789
Kco Group 2	8	9.0%			5	12.2%			5	8.6%			12	6.3%
Kco Group 3	14	15.7%			5	12.2%			6	10.3%			35	18.5%
Kco Group 4	51	57.3%			21	51.2%			39	67.2%			104	55.0%

Notes: TLco is overall gas transfer; Kco is gas transfer corrected for alveolar ventilation. % values indicate the proportion of each group with individual categorical characteristics. Significant P-values are given in bold.

Abbreviations: COPD, chronic obstructive pulmonary disease; FVC, forced vital capacity; FEV₁, forced expired volume in 1 second; N/A, not available; SD, standard deviation; RV, residual volume; TLC, total lung capacity.