Table 4. Multivariate Cox regression analysis of clinical characteristics affecting the median OS in stage IV NSCLC patients with EGFR-TKIs therapy.

Affecting factors	β	SE	Wald	Sig.	Exp (B)	95% CI	Sig.
Smoking history	0.234	0.32	0.535	0.464	1.264	0.675–2.365	0.026
Brain metastasis	−0.838	0.297	7.949	0.005	0.432	0.241–0.774	0.021
ECOG score	1.81	0.342	28.092	0	6.112	3.129–11.938	0