Table 2– Relationship between 6-min walking distance and peak oxygen uptake (V′_O₂peak) or peak work in chronic respiratory disease

First author [ref.]	Diagnosis	Subjects n	V′_O₂peak		Peak work
First author [ref.]	Diagnosis	Subjects n	Pearson’s r	Spearman’s rho	Pearson’s r	Spearman’s rho
Wijkstra [30]	COPD	40			0.81
Rejeski [17]	COPD	209	0.64
Chuang [31]	COPD	27	0.40
Oga [32]	COPD	36		0.64		0.64
Carter [33]	COPD	124	0.54		0.59
Satake [34]	COPD	12			0.64
Turner [35]	COPD	20	0.73		0.83
Starobin [36]	COPD	50	0.58
Hill [37]	COPD	50	0.63		0.75
Luxton [38]	COPD	22			0.63
Díaz [39]	COPD	81	0.78
Kozu [11]	COPD	45	0.80		0.80
Sillen [40]	COPD	2906	0.67
Eaton [12]	IPF	29		0.78
Kozu [11]	IPF	35			0.80
Holland [41]	ILD	14			0.93
Dale [42]	Asbestos-related pleural disease	25	0.53		0.58
Miyamoto [43]	PAH	27	0.70
Deboeck [44]	PAH	20	0.48
Fowler [45]	EIPAH	17	0.72
Baldi [46]	LAM	40	0.55
Cahalin [5]	End-stage lung disease, pre transplant	30	0.73
Ross [47]	Mixed chronic lung diseases, many pre transplant	48	0.59

COPD: chronic obstructive pulmonary disease; IPF: idiopathic pulmonary fibrosis; ILD: interstitial lung disease; PAH: pulmonary arterial hypertension; EIPAH: exercise-induced PAH; LAM: lymphangioleiomyomatosis.