Colon cancer care and survival: income and insurance are more predictive in the USA, community primary care physician supply more so in Canada

Table 2 Effects of interactions of neighborhood poverty, health insurance, community physician supplies and country on 10-year survival of non-metastasized colon cancer: California and Ontario, 1996—2010

	California			Ontario
Baseline		10-Year survival	Rate ratio		10-Year survival	Rate ratio	Canada/United States
Observed group	Sample	Rate, %	95 % CI	Sample	Rate, %	95 % CI	Rate ratio	95 % CI
Less than 30 % vs 30 % or more of households poor in neighborhood
Lower poverty	3,078	42.1		1,368	40.4		0.96	0.89, 1.03
High poverty	1,496	33.3	0.79	692	38.2	0.95	1.15	1.02, 1.30
			0.73, 0.86			0.86, 1.05
Privately insured vs uninsured or publicly insured
Private	2,065	40.8		2,060	38.7		0.95	0.88, 1.02^a
Uninsured or public	2,509	32.8	0.80				1.18	1.09, 1.28^a
			0.74, 0.86
Less than 7.5 vs 7.5 or more primary care physicians per 10,000 population in community
Lower PCP density	4,032	38.5		1,238	36.4		0.95	0.88, 1.02
High PCP density	542	42.8	1.11	822	48.2	1.32	1.13	1.00, 1.28
			1.00, 1.23			1.19, 1.46
Less than 2 vs 2 or more gastroenterologists per 100,000 population in community
Lower GE density	651	35.9		1,953	37.0		1.03	0.92, 1.16
High GE density	3,923	41.2	1.15	107	57.6	1.56	1.40	1.16, 1.70
			1.03, 1.28			1.28, 1.91

Notes. 6,634 incident non-metastasized cases diagnosed between 1996 and 2000 were followed to 2010: 4,574 in California and 2,060 in Ontario. Rates were directly adjusted for age and stage using the California-Ontario population of cases as the standard (age categories: 25–59, 60–69, 70–79 and 80 and older; stage categories: I, II and III). Statistically significant rate ratios are bolded. The adjusted very early diagnosis (stage I) rate of 27.4 % did not differ between-countries. The adjusted 10-year survival rate of 39.2 % did not differ between-countries
^aBoth groups in the USA were compared with the Canadian group all of whom were Medicare covered

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