Table 2– Associations of titrated oxygen requirement (TOR) with survival time

	TOR L·min⁻¹					HR per 1-L·min⁻¹ increase in TOR
	0	1–2	3–6	8–15^#	p_trend	HR (95% CI)	p-value
Derivation cohort^¶
Unadjusted HR (95% CI)	Ref.	3.7 (1.1–13)	5.3 (1.6–18)	7.5 (2.1–27)	0.003	1.14 (1.06–1.24)	<0.001
Adjusted HR (95% CI)
Model 1	Ref.	1.8 (0.5–6.9)	3.1 (0.8–11)	6.7 (1.7–26)	0.004	1.16 (1.06–1.27)	0.001
Model 2	Ref.	1.9 (0.5–7.3)	3.0 (0.8–11)	6.7 (1.7–25)	0.005	1.16 (1.06–1.27)	0.001
Validation cohort⁺
Unadjusted HR (95% CI)	Ref.	2.2 (0.7–7.2)	1.2 (0.4–3.3)	7.7 (2.7–22)	<0.001	1.13 (1.06–1.20)	<0.001
Adjusted HR (95% CI)
Model 1	Ref.	1.4 (0.4–5.4)	0.7 (0.2–2.4)	3.8 (1.01–15)	0.01	1.10 (1.01–1.19)	0.02
Model 2	Ref.	1.4 (0.4–5.3)	0.7 (0.2–2.3)	3.9 (1.05–15)	0.01	1.10 (1.01–1.18)	0.02

Model 1 was adjusted for age, 6-min walk distance and oxygen saturation at the end of the 6-min walk test. Model 2 is model 1 plus adjustment for forced vital capacity % predicted. HR: hazard ratio; p_trend: p-value for trend; ref.: reference group. ^#: two participants in the validation cohort who were titrated to 25 L·min⁻¹ via non-rebreather mask were included in this group; ^¶: n=104; ⁺: n=151.