Table 3.

Multivariable Cox proportional hazards model for factors influencing the risk of osteoporotic fracture among post-menopausal women treated for breast cancer in Ontario, Canada from 2005 to 2012 (N = 12,077).

Characteristics	Units	HR	95% CI	P-value
Endocrine therapy	AI vs. Tamoxifen	1.09	0.96–1.23	0.18
Age	Per Year	1.07	1.06–1.08	<.0001
Charlson comorbidity index	High vs. Low	1.18	1.06–1.31	0.002
History of osteoporosis or osteoporotic fracture	Yes vs. No	1.42	1.24–1.62	<0.001
Previous use of steroids	Yes vs. No	1.30	1.06–1.60	0.012
Previous use of bisphosphonate	Yes vs. No	1.19	1.05–1.35	0.006
Previous use of chemotherapy	Yes vs. No	0.89	0.72–1.10	0.27
Duration of endocrine therapya	Per Year	0.97	0.91–1.02	0.20

AI: Aromatase inhibitor, HR: hazard ratio, CI: confidence interval.

Charlson comorbidity index: High (≥2) vs. Low (0–1 or no hospitalization).

Patients censored at death, end of follow-up (March 2017) and upon a switch of endocrine therapy (aromatase inhibitor to tamoxifen or vice versa).

^aTime-dependent co-variate.