Table 2.

6MWD

Group	6MWD change, n		Total
	Improved (Δd ≥54 min)	Unimproved (Δd <54 min)
LTOT	10	48	58
NPPV + LTOT*	21	36	57
Total	31	84	115

Note:

^*Chi-square test, P=0.02.

Abbreviations: LTOT, long-term oxygen therapy; 6MWD, 6-min walk distance; NPPV, noninvasive positive pressure ventilation.