Table 3.

Cox proportional hazard model for overall survival

Variable	Reference	Univariate analysis			Multivariate analysis
		Hazard ratio	95% CI	p-value	Hazard ratio	95% CI	p-value
Age
≥ 75 yr	< 75 yr	0.62	0.31-1.23	0.172	-	-	-
Smoking history
Former or current	Never	0.66	0.46-0.96	0.028	0.65	0.44-0.94	0.024
Histology
Squamous cell carcinoma	Adenocarcinoma	0.92	0.62-1.38	0.697	-	-	-
Brain metastasis
Yes	No	1.40	0.93-2.11	0.110	-	-	-
Liver metastasis
Yes	No	2.38	1.52-3.75	< 0.001	2.18	1.37-3.47	0.001
ECOG PS
2	0-1	1.60	0.97-2.65	0.067	-	-	-
Previous treatment line
≥ 2	1	1.42	0.94-2.15	0.094	-	-	-
Immune-related AE
Yes	No	0.44	0.29-0.67	< 0.001	0.50	0.33-0.76	0.001
AE
Yes	No	0.77	0.44-1.35	0.360	-	-	-
EGFR
Positive	Negative	0.94	0.52-1.72	0.854	-	-	-

CI, confidence interval; ECOG PS, Eastern Cooperative Oncology Group performance status; AE, adverse effect; EGFR, epidermal growth factor receptor.