Table 3. Univariate and multivariate Cox proportional hazards regression analysis of predictive classifications for progression-free survival in the programmed cell death protein 1 antibody plus chemotherapy group.

Characteristics	Univariate analysis				Multivariate analysis
	HR	95% CI	P		HR	95% CI	P
Gender (male vs. female)	0.606	0.330–1.112	0.11
Age (≥65 vs. <65 years)	0.862	0.538–1.382	0.54
Smoking history (yes vs. no)	0.758	0.442–1.301	0.32
Histology (squamous vs. non-squamous)	1.064	0.665–1.703	0.80
Lung metastasis (yes vs. no)	1.393	0.858–2.262	0.18
Pleural metastasis (yes vs. no)	0.892	0.556–1.431	0.63
Abdominal metastasis (yes vs. no)	1.181	0.675–2.068	0.56
Brain metastasis (yes vs. no)	1.077	0.564–2.058	0.82
Stage (IVB vs. IVA)	1.122	0.695–1.810	0.64
Platelet (≥350 vs. <350 ×109/L)	2.136	1.233–3.700	0.007		2.013	1.163–3.485	0.01
D-dimer (>500 vs. ≤500 ng/mL)	2.114	1.231–3.631	0.007		2.031	1.181–3.492	0.01

HR, hazard ratio; CI, confidence interval.