Table 3.

Among 887 postmenopausal bisphosphonate users with breast cancer, fracture incidence, adjusted hazard rate, and 95% confidence interval of fracture associated with a 5 year increase in duration of bisphosphonate use^a

Exposure	Women (No.)	Fractures		Model 1: Adjusted for Age and Race HR (95% CI)cd	Model 2: Adjusted for a Priori Variables HR (95% CI)ce	Model 3: Adjusted for Age, Race, Endocrine Therapy, and Significant Variables HR (95% CI)cf
		No.b	Incidence per 1,000 Person-years
Bisphosphonate use (5 year increase)	887	142	58.4	1.21 (0.95–1.53)	1.29 (1.00–1.66)	1.28 (1.00–1.63)

Abbreviations: CI, confidence interval; HR, hazard ratio.

^a5 years is equivalent to the interquartile range;

^bNumber of fractures during all follow-up years;

^cFollow-up period is from completion date of 2008–9 medication inventory to end of study in 2013–14;

^dModel 1: Cox proportional hazards model adjusted for age and race;

^eModel 2: Cox proportional hazards model adjusted for selective estrogen receptor modulator use, aromatase inhibitor use, stage of cancer, age, race, parental hip fracture, BMI, current smoking, alcohol intake ≥ 3 units/day rheumatoid arthritis, glucocorticoid use ≥ 3 months, risk of hip fracture within 5 years calculated by WHI 11-item fracture risk algorithm, current calcium supplement use, calcitonin use in past 10 years, estrogen use in past 10 years, diabetes mellitus treated with shots or pills, recreational physical activity, and general health rating and stratified by history of fracture after age 54;

^fModel 3: Cox proportional hazards model adjusted for characteristics that were significantly associated with incident fracture after adjustment for duration of bisphosphonate use (rheumatoid arthritis, recreational physical activity) and a priori adjusted for age, race, history of selective estrogen receptor modulator use, history of aromatase inhibitor use, and stage of cancer and stratified by history of fracture after age 54.