Table 5.

Cox mixed-effects multiple regression analyses for outcome of local recurrence

Variable	Univariable regression		Multivariable model
	HR (95% CI)	P	HR (95% CI)	P
Age (per decade increase in age)	1.05 (0.91 – 1.22)	0.49	1.13 (0.95 – 1.34)	0.18
Depth (deep vs superficial)	3.37 (1.46 – 7.80)	0.004 *	3.27 (1.20 – 8.21)	0.02 *
Maximal Diameter (cm)	1.05 (1.02 – 1.08)	0.002 *	1.03 (0.99 – 1.07)	0.15
Margin
Micro + vs Negative	3.24 (1.74 – 6.03)	<0.001 *	3.76 (2.20 – 8.44)	<0.001 *
Gross + vs Negative	5.18 (2.60 – 10.30)	<0.001 *	5.28 (2.54 – 11.32)	<0.001 *
Radiotherapy (yes vs no)	0.64 (0.39 – 1.05)	0.07	0.46 (0.26 – 0.80)	0.01 *
Chemotherapy (yes vs no)	1.00 (0.63 – 1.59)	0.99	1.14 (0.69 – 2.01)	0.64
Year of Treatment	1.03 (0.99 – 1.06)	0.12	1.01	0.53
††Treating Institution	n/a	0.004	n/a	1

(†Variables in model selected based on a priori determination (CT and RT) and univariable cox analysis with p<0.10), ††Controlling for random effects of treating institution)

(n=343, 27 observations deleted due to missingness)