Table 3.

Univariate and multivariate Cox regression analysis of factors associated with disease-free survival of patients with papillary thyroid carcinoma

	Univariate			Multivariate
	HR	95% CI	p values	HR	95% CI	p values
Male	1.47	0.83–2.61	0.1900
Age <40 years	1.97	1.18–3.31	0.0095	5.23	1.46–18.77	0.0112
Age ≥60 years	2.62	1.61–4.24	0.0001	4.10	1.41–11.89	0.0094
Tumor >4 cm	2.73	1.68–4.46	0.0001
Ex2	2.58	1.60–4.15	0.0001
cN1b	3.63	2.25–5.84	<0.0001	2.82	1.20–6.65	0.0178
Aggressive type	5.81	3.58–9.43	<0.0001	2.13	0.84–5.41	0.1100
Ki-67 LI >10%	6.34	3.72–10.79	<0.0001	15.33	4.13–56.96	0.00005
Ki-67 LI 5–10%	3.47	2.06–5.85	<0.0001	9.33	2.98–29.21	0.00013
Biochemically PD	12.04	6.31–22.99	<0.0001	excluded
Tg-DT <2 years	13.54	6.16–29.76	<0.0001	excluded

HR = Hazard ratio; CI = confidence interval; Ex2 = significant extrathyroid extension; Biochemically PD = biochemically persistent disease; Tg-DT = thyroglobulin doubling time. For the multivariate analysis, biochemically PD and Tg-DT were excluded from the analysis because these factors were strongly associated with Ki-67 LI.