Table 2.

Cox multivariable regression of independent predictors of survival with time to surgery modeled as a categorical variable by quartile

		95% Confidence Interval
Predictor	Hazard Ratio	Lower	Upper	p-value
Age (per year)	1.04	1.03	1.05	<0.001
Sex (female)	0.86	0.68	1.09	0.20
Race (reference: White)
Black	1.21	0.62	2.37	0.58
Other	1.22	0.45	3.29	0.70
Year of diagnosis (per year)	0.98	0.95	1.01	0.20
CDCC score (reference: 0)
1	1.06	0.88	1.28	0.53
2+	1.23	0.90	1.69	0.19
Insurance status (reference: private)
Government	1.01	0.81	1.24	0.96
None	1.51	0.78	2.90	0.22
Facility location (reference: metro)
Urban	1.29	1.03	1.62	0.03
Rural	1.19	0.63	2.26	0.60
Facility type (reference: non-academic)
Academic/Research Program	0.98	0.79	1.23	0.87
Distance to treatment center (per mile)	0.999	0.997	1.000	0.02
Facility geography (reference: New England)
Middle Atlantic (nj,ny,pa)	1.38	0.93	2.06	0.11
South Atlantic (dc,de,fl,ga,md,nc,sc,va,wv)	1.12	0.75	1.66	0.58
East North Central (il,in,mi,oh,wi)	1.37	0.94	2.02	0.11
East South Central (al,ky,ms,tn)	1.17	0.72	1.92	0.52
West North Central (ia,ks,mn,mo,nd,ne,sd)	1.10	0.71	1.70	0.67
West South Central (ar,la,ok,tx)	1.18	0.72	1.94	0.51
Mountain (az,co,id,mt,nm,nv,ut,wy)	1.62	1.00	2.63	0.05
Pacific (ak,ca,hi,or,wa)	1.02	0.67	1.56	0.92
Center volume (reference: Q1 ≤1 a year)
Q2 (>1-3)	0.97	0.69	1.36	0.86
Q3 (>3-8)	0.97	0.69	1.36	0.87
Q4 (>8)	0.66	0.46	0.96	0.03
Tumor size	1.000	0.999	1.002	0.96
Grade (reference: well differentiated)
Moderately differentiated	1.11	0.86	1.43	0.41
Poorly differentiated	2.13	1.66	2.73	<0.001
Time to surgery (reference: Q1)
Q2	0.83	0.67	1.04	0.10
Q3	0.91	0.72	1.14	0.40
Q4	0.93	0.73	1.18	0.55