Table 1. Mortality rate ratios (MRRs) for women with SMI, women with breast cancer and women with both SMI and breast cancer compared to women with neither SMI nor breast cancer in Denmark in 1980–2012 (N = 2,665,963).

MRR, neither SMI nor breast cancer	MRR, SMI (95% CI)	MRR, breast cancer (95% CI)	MRR, SMI and breast cancer (95% CI)	AP due to interaction, SMI and breast cancer (95% CI)
1 (ref)	2.18 (2.14–2.22)	2.44 (2.42–2.47)	4.27 (3.98–4.57)	15.0% (9.0–20.9)

Abbreviations: MRR: mortality rate ratio; SMI: severe mental illness; CI: confidence interval. The MRRs were adjusted for age and calendar period