Table 2.

Univariate and multivariate Cox regression models of factors associated with OS

Characteristics	Univariate			Multivariate
	HR	95% CI	P value	HR	95% CI	P value
Gender
Female	reference			reference
Male	0.72	0.57–0.91	0.0064	0.86	0.68–1.10	0.228
Age
≤65	reference			reference
>65	1.49	1.16–1.91	0.0015	1.30	1.01–1.68	0.045
Race
Non-Hispanic White	reference
Hispanic White	1.21	0.89–1.66	0.23
Black	1.10	0.68–1.80	0.69
Others	0.98	0.71–1.34	0.89
T stage
T1/2	reference
T3	1.31	0.73–2.36	0.36
T4	1.41	0.82–2.44	0.21
N stage
N0	reference
N1	0.91	0.69–1.19	0.47
Tumor Diameter
≤6 cm	reference			reference
>6 cm	1.62	1.27–2.07	0.0001	1.19	1.09–1.29	< 0.0001
Tumor Extension
Limited to Thyroid	reference
Extrathyroidal Extension	0.96	0.71–1.29	0.8
Distant Lymph Node Metastasis
No	reference
Yes	1.12	0.87–1.44	0.37
Bone Metastasis
No	reference
Yes	0.85	0.64–1.13	0.27
Brain Metastasis
No	reference
Yes	1.06	0.65–1.73	0.82
Liver Metastasis
No	reference
Yes	0.95	0.62–1.45	0.8
Lung Metastasis
No	reference			reference
Yes	1.54	1.11–2.15	0.01	1.55	1.10–2.17	0.011
Multiple Organ Metastases
No	reference
Yes	1.10	0.83–1.46	0.5
Marital status
Single (never married)	reference
Married	0.89	0.62–1.28	0.54
Divorced/Separated/Widowed	1.30	0.87–1.94	0.21
Unknown	0.88	0.27–2.90	0.83
Surgery to Primary Site
No	reference			reference
Non-thyroidectomy	0.64	0.44–0.94	0.02	0.73	0.50–1.07	0.108
Thyroidectomy	0.51	0.38–0.67	< 0.0001	0.59	0.44–0.79	< 0.0001
Radiotherapy
No	reference			reference
Yes	0.60	0.48–0.77	< 0.0001	0.70	0.54–0.91	0.007
Chemotherapy
No	reference			reference
Yes	0.39	0.30–0.50	< 0.0001	0.54	0.42–0.70	< 0.0001