Hyperoxia for accidental hypothermia and increased mortality: a post-hoc analysis of a multicenter prospective observational study

Table 4 28-day mortality in subgroup analyses

Subgroups	Hyperoxia	No hyperoxia	OR	95% CI
Age
< 65 years	10.3% (7.3–19.8%)	11.6% (2.0–21.2%)	0.87	0.22–3.50
≥ 65 years	37.8% (31.7–43.9%)	26.4% (20.8–31.9%)	1.70	1.15–2.50
Chronic cardiopulmonary disease*
(−)	27.1% (21.6–32.7%)	19.8% (14.8–24.9%)	1.50	0.99–2.30
( +)	78.9% (66.0–91.9%)	48.7% (33.0–64.4%)	3.95	1.45–10.74
Hemodynamic instability on hospital arrival
SBP ≥ 90 mmHg	38.2% (30.9–45.4%)	18.4% (12.3–24.6%)	2.73	1.64–4.56
SBP < 90 mmHg	28.3% (20.0–36.6%)	30.2% (22.3–38.2%)	0.91	0.52–1.59
Severity of hypothermia
< 28 °C	34.9% (27.3–42.4%)	24.0% (17.8–30.3%)	1.69	1.05–2.73
≥ 28 °C	33.1% (25.1–41.1%)	24.3% (16.0–32.6%)	1.54	0.87–2.75
Without hypoxia**	34.0% (28.5–39.5%)	22.2% (17.1–27.3%)	1.81	1.23–2.66

OR Odds ratio, CI Confidence interval, SBP Systolic blood pressure. IPW analyses were performed in each subgroup
*Chronic cardiopulmonary disease included congestive heart failure and chronic lung diseases
**Hypoxia was defined as a PaO₂ level less than 60 mmHg

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