Table 4.

Stratified models and sensitivity analyses for death, with and without CT extension

	Stratified by SO2 level		Stratified by symptom onset		Restricted populations
	< 95%	≥ 95%	< 8 days before ER presentation	≥ 8 days before ER presentation	Excluding patients over 85 y/o	Excluding patients with > 60% CT extension	Excluding patients who died within 48 h
Number of observations (N)	358	508	564	302	818	799	859
Number of deaths (n)	73	20	76	17	67	64	86
HR of CT extension (95% CI)
< 20%	1	1	1	1	1	1	1
20–39%	1.40 (0.57–3.44)	1.30 (0.40–4.18)	1.12 (0.54–2.35)	1.86 (0.20–16.97)	1.72 (0.69–4.32)	1.28 (0.61–2.69)	1.48 (0.72–3.04)
40–59%	2.56 (1.00–6.50)	2.81 (0.67–11.73)	2.17 (0.99–4.75)	3.59 (0.36–35.27)	3.91 (1.52–10.08)	2.54 (1.16–5.57)	2.80 (1.32–5.94)
≥ 60%	8.11 (3.12–21.12)	10.11 (1.60–63.78)	5.75 (2.48–13.33)	9.44 (1.01–88.38)	9.96 (3.68–26.95)	-	8.95 (3.99–20.09)
cvAUC (BBC 95% CI)
Model with clinical variables only	0.889 (0.822–0.914)	0.949 (0.867–0.963)	0.918 (0.882–0.940)	0.921 (0.811–0.974)	0.929 (0.888–0.949)	0.907 (0.899–0.952)	0.924 (0.891–0.940)
Model with clinical variables + CT extension	0.907 (0.861–0.931)	0.952 (0.885–0.966)	0.920 (0.891–0.945)	0.929 (0.850–0.971)	0.943 (0.910–0.957)	0.915 (0.906–0.955)	0.936 (0.906–0.949)

Characteristics of the sensitivity analyses, respectively stratified by SO2 and days before symptoms onset, and excluding patients older than 85 years, > 60% CT extension, and those who died within 48 h. SO2, oxygen saturation level; HR, hazard ratio; cvAUC, cross-validated area under the curve; CI, confidence interval; BBC 95% CI, bootstrap corrected 95% confidence interval