Prognosis after Intensive Care for COPD Exacerbation in Relation to Long-Term Oxygen Therapy: A Nationwide Cohort Study

Figures & data

Figure 1. Flow diagram for inclusion and exclusion of patients.

Table 1. Data on baseline characteristics at ICU admission, treatment, and outcomes.

	Total cohort	No LTOT	LTOT	Missing
n	4648	4198	450
Female sex	2812 (60.5%)	2528 (60.2%)	284 (63.1%)
Age
40–60 years	415 (8.9%)	389 (9.3%)	26 (5.8%)
60–70 years	1421 (30.6%)	1317 (31.4%)	104 (23.1%)
70–75 years	924 (19.9%)	810 (19.3%)	114 (25.3%)
75–80 years	922 (19.8%)	811 (19.3%)	111 (24.7%)
80–85 years	966 (20.8%)	871 (20.7%)	95 (21.1%)
SAPS3 score (median, IQR)	59 (52–67)	59 (52–67)	60 (54–68)	11.8%
Co-morbidities*
Chronic heart failure	570 (12.3%)	516 (12.3%)	54 (12.0%)
Metastatic cancer	142 (3.1%)	132 (3.1%)	10 (2.2%)
Hematologic malignancy	27 (0.6%)	23 (0.6%)	4 (0.9%)
Liver cirrhosis	18 (0.4%)	16 (0.4%)	2 (0.4%)
AIDS	8 (0.2%)	7 (0.2%)	1 (0.2%)
Special therapy^‡	202 (4.3%)	163 (3.9%)	39 (8.7%)
Location before ICU
Emergency room	2410 (51.9%)	2165 (51.6%)	245 (54.4%)
Ward	2025 (43.6%)	1842 (43.9%)	183 (40.7%)
Other	213 (4.6%)	191 (4.5%)	22 (4.9%)
pH (median, IQR)	7.27 (7.20–7.35)	7.27 (7.19–7.35)	7.29 (7.21–7.35)	16.0%
PaO2 (median, IQR)	8.6 (7.0–10.5)	8.7 (7.1–10.6)	7.9 (6.4–9.6)	19.3%
PaO2/FiO2 ratio (median, IQR)	0.237 (0.178– 0.300)	0.240 (0.180–0.303)	0.223 (0.162–0.276)	41.1%
Unconscious	585 (14.5%)	524 (14.4%)	61 (15.1%)	13.0%
Respiratory support				43.4%
NIV only	1916 (72.8%)	1687 (71.5%)	229 (84.2%)
Invasive ventilation only	447 (17.0%)	419 (17.8%)	28 (10.3%)
Invasive ventilation after NIV	268 (10.2%)	253 (10.7%)	15 (5.5%)
Hours in ICU (median, IQR)	27.0 (14.8–60.3)	27.7 (15.0–63.2)	23.0 (12.2–42.8)
ICU mortality	464 (10.0%)	387 (9.2%)	77 (17.1%)
30-day mortality	1212 (26.1%)	1039 (24.7%)	173 (38.4%)
1-year mortality	2133 (45.9%)	1816 (43.3%)	317 (70.4%)
Median survival time (IQR), days	415 (24–1502)	520 (31–1811)	92 (6–430)

* Co-morbidities according to SIR. Missing data considered as no diagnosis.

‡ Special therapy = systemic corticosteroids daily ≥0.3 mg/kg prednisolone within the last 6 months, radiotherapy for invasive malignancy in the last 6 months, or chemotherapy.

Abbreviations: ICU, intensive care unit; IQR, inter-quartile range; LTOT, long-term oxygen therapy; NIV, noninvasive ventilation; SAPS3, Simplified Acute Physiology Score 3.

Figure 2. Kaplan-Meier plots of survival stratified by (a) LTOT, and by (b) LTOT and sex with 95% CI (shaded areas).

Table 2. Multivariable regression models for 30-day mortality and one-year mortality.

	30-day mortality OR (95% CI)	One-year mortality HR (95% CI)
N	4100	4100
LTOT at ICU admission	1.83 (1.46–2.28)	1.79 (1.58–2.02)
Sex
Female	1 (reference)	1 (reference)
Male	1.13 (0.97–1.31)	1.16 (1.06–1.27)
Age group
40–60 years	1 (reference)	1 (reference)
60–70 years	1.72 (1.18–2.51)	1.33 (1.07–1.66)
70–75 years	2.55 (1.74–3.73)	1.84 (1.48–2.30)
75–80 years	3.51 (2.40–5.13)	2.32 (1.87–2.89)
80+ years	4.33 (2.97–6.30)	2.86 (2.31–3.54)
SAPS3 (excluding age)	1.05 (1.05–1.06)	1.03 (1.02–1.03)

Abbreviations: CI, confidence interval; HR, hazard ratio; ICU, intensive care unit; LTOT, long-term oxygen therapy; OR, odds ratio; SAPS3, Simplified Acute Physiology Score 3.

Table 3. Multivariable regression models including respiratory support on the subgroup of patients with complete data.

	30-day mortality OR (95% CI)	One-year mortality HR (95% CI)
n	2417	2417
LTOT at ICU admission	2.31 (1.75–3.05)	1.90 (1.63–2.23)
Sex
Female	1 (reference)	1 (reference)
Male	1.15 (0.95–1.39)	1.14 (1.02–1.28)
Age group
40–60 years	1 (reference)	1 (reference)
60–70 years	2.03 (1.22–3.37)	1.35 (1.01–1.81)
70–75 years	2.89 (1.73–4.84)	1.88 (1.40–2.53)
75–80 years	4.10 (2.45–6.85)	2.41 (1.80–3.23)
80+ years	5.12 (3.07–8.54)	2.81 (2.10–3.77)
SAPS3 (excluding age)	1.05 (1.04–1.06)	1.03 (1.02–1.03)
Respiratory support
NIV only	1 (reference)	1 (reference)
Invasive ventilation only	1.03 (0.80–1.32)	0.89 (0.76–1.04)
Invasive ventilation after NIV	1.18 (0.87–1.60)	0.85 (0.69–1.03)

Abbreviations: CI, confidence interval; HR, hazard ratio; ICU, intensive care unit; LTOT, long-term oxygen therapy; NIV, noninvasive ventilation; OR, odds ratio; SAPS3, Simplified Acute Physiology Score 3.