Table I.

Univariate and multivariate Cox regression analysis of factors associated with disease-free survival (DFS).

	Univariate analysis			Multivariate analysis
All variables	P-value	HR	95% CI	P-value	HR	95% CI
Age (years)
<45		1
≥45	0.939	1.030	0.488–2.172	nd	nd	nd
Sex
Male		1			1
Female	0.273b	0.641	0.290–1.418	0.152	0.530	0.222–1.265
Maximum tumor size (cm)
<4		1
≥4	0.619	1.229	0.545–2.771	nd	nd	nd
Multifocality
Unifocal		1
Multifocal	0.794	1.108	0.515–2.383	nd	nd	nd
ETE
No		1
Yes	0.952	1.024	0.470–2.230	nd	nd	nd
LNM
N0		1			1
N1	0.012c	3.242	1.300–8.083	0.112	2.400	0.816–7.056
T stage
T1-T2		1	1
T3-T4	0.326b	1.451	0.690–3.052	0.611	1.239	0.542–2.835
TNM stage
I–II		1			1
III–IV	0.027c	2.323	1.102–4.895	0.100	2.117	0.867–5.173
Histological type
Classical PTC		1			1
Follicular PTC	0.369b	0.575	0.172–1.925	0.672	1.312	0.373–4.610
Tall-cell PTC	0.557	0.548	0.073–4.086	0.190	0.251	0.032–1.980
CTSS
≥ cut-offa	0.009d	2.705	1.287–5.688	0.031c	2.649	1.095–6.409
< cut-offa		1			1
IRS1
≥ cut-offa	0.007d	0.360	0.171–0.756	0.208	0.551	0.218–1.392
< cut-offa		1			1

^aCut-off was calculated by non-parametric receiver operating characteristic analyses to predict disease-free survival; PTC, papillary thyroid cancer; ETE, extrathyroidal extension; LNM, lymph node metastasis; TNM, tumor-node-metastases; HR, hazard ratio; CI, confidence interval; nd, not done

^bP<0.5

^cP<0.05

^dP<0.01.