Table 7. Univariate and multivariate Cox regression models for predicting overall survival.

Variables	Univariate analysis			Multivariate analysis
	HR	95% CI	P value	HR	95% CI	P value
Age ≤50 years	0.785	[0.252–2.439]	0.675
Gender, male	0.606	[0.191–1.919]	0.394
Tumor size >2 cm	4.385	[1.375–13.989]	0.012	2.847	[0.870–9.312]	0.084
Multifocality	1.536	[0.458–5.146]	0.487
Extrathyroidal extension	2.965	[0.887–9.908]	0.077
Bilateral	0.649	[0.083–5.095]	0.681
Preoperative calcitonin ≤300 ng/L	6.943	[0.881–54.724]	0.066
Pathologic T classification, pT3/T4	2.801	[0.838–9.361]	0.094
Pathologic N classification, pN0/N1a	14.947	[1.922–116.264]	0.010	4.521	[0.516–39.627]	0.173
Resected lymph nodes ≤10	64.123	[0.597–6890.514]	0.081
Metastasized lymph nodes ≤10	3.251	[0.971–10.884]	0.056
Lymph node ratio ≤0.24	15.994	[2.063–124.023]	0.008	10.061	[1.222–82.841]	0.032
AJCC clinical stage, III/IV stages	43.503	[0.332–5694.725]	0.129
Biochemical cure	1.870	[0.467–7.488]	0.376

Notes:

HR, hazard ratio; CI, confidence interval. The bold part of the P value represents P < 0.05.