Table 2. Effect of altered thymic density and prognostic factors on progression-free survival after immune checkpoint inhibitor therapy in univariate and multivariate Cox regression models (n=412).

Parameter	Univariate analysis			Multivariate analysis
	Hazard ratio (95% CI)	P value		Hazard ratio (95% CI)	P value
Gender
Male	Reference
Female	1.17 (0.79, 1.74)	0.44
Age (years)
<65	Reference
≥65	1.07 (0.81, 1.41)	0.63
Body mass index (kg/m2)
< median*	Reference			Reference
≥ median	0.74 (0.51, 1.07)	0.11		0.77 (0.53, 1.12)	0.18
Total bilirubin (mg/dL)	1.00 (0.97, 1.03)	0.89
A/G ratio	0.61 (0.39, 0.95)	0.03		0.62 (0.40, 0.97)	0.04
Smoking
No	Reference
Yes	0.85 (0.65, 1.11)	0.24
Hypertension
No	Reference
Yes	1.13 (0.85, 1.49)	0.41
Hyperlipidemia
No	Reference
Yes	0.89 (0.66, 1.19)	0.43
Neutrophil to lymphocyte ratio
≤2	Reference			Reference
>2	1.45 (0.98, 2.16)	0.07		0.96 (0.62, 1.47)	0.84
Platelet to lymphocyte ratio
≤150	Reference			Reference
>150	1.68 (1.25, 2.26)	<0.001		1.36 (0.99, 1.88)	0.059
Pathological types
Adenocarcinoma	Reference
Squamous carcinoma	0.74 (0.56, 0.98)	0.04
Other	0.80 (0.45, 1.43)	0.45
Stages
Stage III	Reference			Reference
Stage IV	2.42 (1.69, 3.45)	<0.001		2.30 (1.59, 3.31)	<0.001
Type of ICIs
PD-1 antibody	Reference
PD-L1 antibody	1.21 (0.76, 1.91)	0.42
Group
Loss	Reference			Reference
Non-loss	1.27 (0.97, 1.66)	0.08		1.33 (1.01, 1.74)	0.042

*, the median body mass index is 25 kg/m². Non-loss, patients with no loss of thymic density; Loss, patients with loss of thymic density; CI, confidence interval; A/G ratio, ratio of albumin to globulin; ICIs, immune checkpoint inhibitors; PD-1, programmed cell death-1; PD-L1, programmed cell death-ligand 1.