Does geography influence the treatment and outcomes of colorectal cancer? A population-based analysis

Table 4 The 5-year overall survival Cox proportional multivariate hazards model

Variable	Event (n (%))	Adjusted HR^a	95%CI	P value
Age quartile^b				<0.0001
Quartile 1	210 (38.75)	1
Quartile 2	234 (44.83)	1.21	1.00 to 1.46
Quartile 3	266 (50.19)	1.59	1.31 to 1.93
Quartile 4	328 (66.67)	2.07	1.69 to 2.53
Gender				0.007
Female	470 (48.81)	1
Male	568 (50.58)	1.19	1.05 to 1.35
Site				0.755
Colon	707 (51.38)	1
Rectosigmoid	103 (50.99)	1.06	0.85 to 1.31
Rectum	228 (44.88)	0.96	0.81 to 1.15
AJCC stage				<0.0001
I	111 (27.54)	1
II	188 (32.70)	1.44	1.12 to 1.86
III	279 (45.74)	2.22	1.71 to 2.87
IV	412 (93.85)	7.67	5.88 to 10.00
Unknown/NA^c	48 (81.36)	3.08	2.14 to 4.45
Income quintile^d				0.004
Quintile 1	271 (58.66)	1
Quintile 2	240 (52.86)	1.07	0.90 to 1.28
Quintile 3	209 (47.83)	0.95	0.79 to 1.14
Quintile 4	159 (42.51)	0.92	0.75 to 1.13
Quintile 5	137 (40.90)	0.77	0.63 to 0.95
NF	22 (91.67)	1.78	1.14 to 2.78
CCI group				<0.0001
CCI count <1	235 (28.08)	1
CCI count = 1	448 (58.56)	2.03	1.70 to 2.42
CCI count >1	355 (73.35)	2.79	2.33 to 3.36
RHA group				0.314
Winnipeg	589 (48.84)	1
North Manitoba	36 (55.38)	0.98	0.69 to 1.39
South Manitoba	239 (48.19)	1.16	0.99 to 1.35
Middle Manitoba	174 (54.55)	1.04	0.87 to 1.23
Surgery				<0.0001
Major surgery	694 (42.63)	0.54	0.40 to 0.73
Local resection	14 (24.14)	0.33	0.18 to 0.58
Polypectomy	26 (37.14)	0.63	0.40 to 0.97
None	304 (92.12)	1
Chemotherapy				<0.0001
No	677 (50.52)	1
Yes	361 (48.39)	0.59	0.50 to 0.69
Radiation therapy				0.126
No	916 (51.29)	1
Yes	122 (40.67)	0.84	0.67 to 1.05
Lymph nodes removed				<0.0001
0 to 12	249 (47.43)	1
>12	440 (39.43)	0.76	0.65 to 0.89
Unknown/not examined^e	349 (78.43)	1.43	1.06 to 1.94

All variables listed are included in the full model. ^aHR >1 relates to higher mortality; ^bquartile 1: age 20 years to 61 years, quartile 2: age greater than 61 years to 72 years, quartile 3: age greater than 72 years to 80 years, and quartile 4: age greater than 80 years to 103 years; ^cone or more elements of the AJCC stage is missing or staging scheme is NA; ^dquintile 1: poorest, quintile 5: richest; ^eunknown number or no lymph nodes examined. AJCC American Joint Committee on Cancer, CCI Charlson comorbidity index, CI confidence interval, HR hazards ratio, NA not applicable, NF not formatted, RHA regional health authority.

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