Long-term oxygen therapy in COPD patients: population-based cohort study on mortality

Figures & data

Figure 1 Flow of participants through different stages of the study.

Abbreviations: COPD, chronic obstructive pulmonary disease; LTOT, long-term oxygen therapy.

Table 1 Patients’ characteristics at baseline

	All patients (n=475)	Incident LTOT users (n=93)		Prevalent LTOT users (n=382)		p-value
		Patients alive	Patients died	Patients alive	Patients died
		n=55 (59%)	n=38 (41%)	n=280 (73%)	n=102 (27%)
Age (years)	69.0±10.0	71.1±9.9	71.8±8.4	66.8±10.2	72.7±8.5	<0.001
Elderly (>65 years of age)	296 (62%)	36 (65%)	28 (74%)	151 (54%)	81 (79%)	<0.001
Sex (male)	323 (68%)	38 (69%)	30 (79%)	184 (66%)	71 (70%)	0.405
Oxygen delivery device
Liquid oxygen	211 (44%)	14 (25%)	4 (11%)	147 (53%)	46 (45%)	<0.001
Concentrator	264 (56%)	41 (75%)	34 (89%)	133 (48%)	56 (55%)	<0.001
	Data available, value*	Data available, value*	Data available, value*	Data available, value*	Data available, value*
Cor pulmonale	373, 243 (65%)	48, 29 (60%)	31, 16 (52%)	214, 143 (67%)	80, 55 (69%)	0.296
Vital capacity (%)	411, 64.0±22.9	49, 58.9±24.3	33, 63.8±22.0	243, 64.8±22.2	86, 64.8±24.1	0.417
FEV1 (%)	417, 43.1±17.1	51, 45.9±18.1	34, 40.0±15.2	246, 42.4±16.5	86, 44.7±18.9	0.306
PaO2 at rest while breathing room air ≤60 mmHg	424, 336 (79%)	51, 43 (84%)	33, 24 (73%)	252, 201 (80%)	88, 68 (77%)	0.594
PaCO2 at rest while breathing room air ≥55 mmHg	423, 18 (4%)	50, 1 (2%)	34, 4 (12%)	251, 9 (4%)	88, 4 (5%)	0.131
PaO2 after 30 min supplemental oxygen ≤60 mmHg	315, 54 (17%)	36, 9 (25%)	22, 3 (14%)	186, 28 (15%)	71, 14 (20%)	0.447
PaCO2 after 30 min supplemental oxygen ≥55 mmHg	317, 35 (11%)	36, 3 (8%)	23, 5 (22%)	187, 21 (11%)	71, 6 (8%)	0.329
Oxygen dose at rest (L)	457, 2.0±1.0	53, 2.1±1.2	37, 2.0±0.9	268, 1.9±0.8	99, 2.3±1.4	0.003
Type 2 respiratory failure	424, 15 (4%)	51, 1 (2%)	33, 2 (6%)	252, 8 (3%)	88, 4 (5%)	0.718
Compliance to LTOT	475, 333 (70%)	55, 36 (65%)	38, 26 (68%)	280, 191 (68%)	102, 80 (78%)	0.215

Notes: Type 2 respiratory failure was defined as PaO₂ <60 mmHg and PaCO₂ >55 mmHg.

* Values are mean with a standard deviation for continuous variables and percentage for categorical variables.

Abbreviations: FEV₁, forced expiratory volume in 1 second; LTOT, long-term oxygen therapy; PaCO₂, carbon dioxide partial pressure; PaO₂, oxygen partial pressure.

Figure 2 Age- and sex-standardized mortality ratios for incident LTOT users (A) and prevalent LTOT users (B).

Abbreviations: CI, confidence interval; LTOT, long-term oxygen therapy; PaCO₂, carbon dioxide partial pressure; PaO₂, oxygen partial pressure; SMR, standardized mortality ratio.

Figure 3 Age-related probability of death among incident LTOT users (A) and prevalent LTOT users (B).

Abbreviation: LTOT, long-term oxygen therapy.

Table 2 Differences of the standardized mortality ratios of oxygen-dependent COPD patients from our cohort compared with an overall COPD population

	Standardized mortality ratios
	Incident LTOT users	Prevalent LTOT users	Overall COPD population^Citation33
Female	5.62	7.78	2.7
Male	9.05	5.33	4.8

Abbreviations: COPD, chronic obstructive pulmonary disease; LTOT, long-term oxygen therapy.

RingbaekTSeersholmNViskumKStandardised mortality rates in females and males with COPD and asthmaEur Respir J200525589189515863648

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