Table 1.

Associations of Country and Socioeconomic Status with 15-Year Node-Negative Breast Cancer Survival

Income group	Ontario				California				Ontario versus California
Income group	n	Rate¹	RR²	95% CI³	n	Rate¹	RR²	95% CI³	RR	95% CI³
Highest	43	0.522	1.00	—	44	0.570	1.00	—	0.92	0.67, 1.26
	31	0.461	0.88	0.54, 1.42	50	0.569	1.00	0.96, 1.04	0.81	0.56, 1.16
	42	0.527	1.01	0.88, 1.16	47	0.482	0.85	0.56, 1.30	1.09	0.67, 1.78
	35	0.576	1.10	0.78, 1.55	42	0.576	1.01	0.65, 1.56	1.00	0.84, 1.20
Middle	34	0.474	0.91	0.54, 1.52	41	0.319	0.56	0.34, 0.92	1.49	0.88, 2.53
	36	0.550	1.05	0.78, 1.42	47	0.521	0.91	0.65, 1.28	1.06	0.80, 1.41
	35	0.493	0.94	0.55, 1.62	44	0.394	0.69	0.45, 1.06⁴	1.25	0.78, 2.01
	46	0.530	1.02	0.65, 1.61	41	0.477	0.84	0.53, 1.33	1.11	0.77, 1.60
	28	0.571	1.09	0.77, 1.54	45	0.479	0.84	0.54, 1.31	1.19	0.80, 1.76
Lowest	36	0.502	0.96	0.60, 1.54	41	0.302	0.60	0.37, 0.97	1.66	1.00, 2.76

n, number of incident breast cancer cases; Rate, directly age-adjusted 15-year survival rate; RR, standardized survival rate ratio; CI, confidence interval.

Bolded RRs and CIs are statistically significant.

All rates were directly age-adjusted using this study’s combined Ontario-California population of cases as the standard (age strata: 25–44, 45–54, 55–64, 65–74 and 75 years or older), so all of the rates are directly comparable.

A survival rate ratio of 1.00 is the within-country baseline.

Confidence intervals are based on the Mantel–Haenszel chi-squared test.

⁴

90% confidence interval does not include the null (0.48, 0.99).