Table 2. Relationship between reduced diffusing capacity of the lung for carbon monoxide (D_LCO) and patient/disease characteristics.

	Trip [41]			Chandra [44]
	DLCO <45%	DLCO ≥45%	p-value	DLCO <43%	DLCO 43–64%	DLCO >64%	p-value
Subjects n	48	118		135	135	138
Age years	67#	46#	<0.001	55¶	47¶	45¶	<0.0001
Males	50	19	0.01	22	21	25	0.74
Former smoker	58	30	0.07
Current smoker	19	18	0.77
6MWD m	275+	390+	0.03
Metabolic equivalents				2.6	3.7	4.2	<0.0001
NYHA WHO FC I/II	21	35	0.05§	9	25	26	<0.0001ƒ
NYHA WHO FC III/IV	79	65		91	75	74
Anti-nuclear antibodies	38	20	0.06	79	55	32	<0.0001
RAP mmHg	7.3+	8.1+	ns	11	11	11	0.83
mPAP mmHg	47+	52+	ns	49	54	54	0.02
CI mL·min−1·m−2	2.3+	2.5+	ns	2	2	2	0.78
PVR Wood Units			ns	11	13	13	0.03
TPVR dyn·s·cm−5	1000+	1004+
HR (95% CI)	3.8 (2.2–6.6)##		<0.001	2.7 (1.9–3.9)##			<0.001
				2.4 (1.1–5.0)¶¶			0.025

Data are presented as %, unless otherwise stated. 6MWD: 6-min walking distance; NYHA: New York Heart Association; WHO: World Health Organization; FC: functional class; RAP: right atrial pressure; mPAP: mean pulmonary artery pressure; CI: cardiac index; PVR: pulmonary vascular resistance; TPVR: total PVR; HR: hazard ratio; ns: nonsignificant. ^#: median age at diagnosis; ^¶: mean age at study entry; ⁺: approximate value based on data from [42]; ^§: FC I/II versus III/IV; ^ƒ: across all groups; ^##: univariate analysis; ^¶¶: multivariate analysis.