Table 3.

Association between oral bisphosphonate use and lung cancer by selected baseline characteristic factors (1993–2013)

Parameter	Oral bisphosphonate use				HR (95% CI)	P for interaction
	Never		Evera
	Cases	Person years	Cases	Person years
Smoking
Never	366	913 445.0	29	106 658.0	0.57 (0.39–0.84)b*	0.02
Ever	1860	877 056.6	220	90 969.5	0.96 (0.83–1.11)c
Former smokers	1233	763 562.6	162	81 502.8	1.05 (0.89–1.24)c
Current smokers	627	113 494.0	58	9466.7	0.85 (0.64–1.12)c
Total calcium intake (mg/day)						0.13
<800	887	626 538.2	68	50 092.0	0.73 (0.57–0.95)d‡
800–1200	513	446 347.3	54	45 243.3	0.97 (0.72–1.29)d
≥1200	857	738 810.2	132	102 724.9	1.00 (0.83–1.20)d

^aUsers reported at least 2 weeks of use; nonusers included never users and those who used for <2 weeks. Baseline oral bisphosphonate use was updated at years 1, 3 and 6 for women in the WHI-CT and at year 3 for women in the WHI-OS.

^*P ≤0.01;

^‡P = 0.02.

^bAdjusted for baseline age, ethnicity, education, alcohol use status, BMI, physical activity, total calcium intake, total vitamin D intake, statins use, and hormone treatment status and stratified on WHI study component.

^cAdditionally adjusted number of cigarettes per day, duration of regular smoking in years among smokers.

^dAdjusted for baseline age, ethnicity, education, smoking status, number of cigarettes per day, duration of regular smoking in years, alcohol use status, BMI, physical activity, total vitamin D intake, and hormone treatment status and stratified on WHI study component.