Table 3.

Harrell’s c-statistic for discrimination ability of Cox proportional hazards models on 3-year overall survival of women aged 50+ years with ER-positive EIBC by country of diagnosis

Model no.	Factors included in the cox regression model for 3 year survival	Harrell’s c-statistic for cox proportional hazards survival model
		England (internal validation)			Wales (external validation)
		In all women*	In women who did receive surgery	In women who did not receive surgery	In all women*	In women who did receive surgery	In women who did not receive surgery
1	Invasive grade, T stage, N stage, HER2 status, IMD status (+receipt of surgery*)	0.804	0.669	0.552	0.782	0.634	0.653
2	Invasive grade, T stage, N stage, HER2 status, IMD status+CCI (+receipt of surgery*)	0.824	0.708	0.618	0.802	0.664	0.679
3	Invasive grade, T stage, N stage, HER2 status, IMD status+SCARF index (+receipt of surgery*)	0.828	0.718	0.625	0.804	0.667	0.691
4	Invasive grade, T stage, N stage, HER2 status, IMD status+CCI+SCARF index (+receipt of surgery*)	0.829	0.719	0.628	0.805	0.673	0.690
5	Invasive grade, T stage, N stage, HER2 status, IMD status+age (+receipt of surgery*)	0.842	0.750	0.638	0.837	0.723	0.703
6	Invasive grade, T stage, N stage, HER2 status, IMD status+CCI+SCARF index+age (+receipt of surgery*)	0.852	0.770	0.663	0.841	0.734	0.715

*The receipt of surgery was only factored in the model that included all women.

CCI, Charlson Comorbidity Index; EIBC, early invasive breast cancer; HER2, Human epidermal growth factor receptor 2; IMD, Index for multiple deprivation; SCARF, secondary care administrative records frailty.