TABLE 3.

Stratified adjusted^a hazard ratios (HRs) for their associations between severe acne and breast cancer in the Sister Study

	Number of cases	Severe/cystic acne diagnosis		Severe and adolescent acne
		HR (95% CI)	Heterogeneity p-value	HR (95% CI)	Heterogeneity p- value
Time-varying menopausal status
Premenopausal	560	1.25 (0.79, 2.00)	0.90	1.16 (0.55, 2.44)	0.67
Postmenopausal	2,459	1.21 (0.94, 2.12)		1.39 (0.96, 2.00)
Race
Non-Hispanic White	2,602	1.22 (0.96, 1.56)	0.95	1.30 (0.92, 1.83)	0.35
Other	422	1.25 (0.63, 2.51)		2.27 (0.74, 6.95)
Parity
Nulliparous	557	1.12 (0.69, 1.81)	0.66	1.04 (0.49, 2.18)	0.43
Parous	2,467	1.26 (0.98, 1.64)		1.45 (1.01, 2.09)
Body mass index (BMI)
Non-obese (<30 kg/m2)	2,084	1.27 (0.97, 1.65)	0.63	1.42 (0.97, 2.06)	0.55
Obese (≥30 kg/m2)	940	1.11 (0.71, 1.75)		1.12 (0.56, 2.21)
Ever hormone therapy use
No	1,639	1.25 (0.93, 1.67)	0.85	1.38 (0.91, 2.09)	0.85
Yes	1,385	1.19 (0.83, 1.73)		1.29 (0.76, 2.20)
Ever hormonal contraceptive use
No	478	0.87 (0.39, 1.94)	0.37	1.89 (0.72, 4.98)	0.48
Yes	2,546	1.27 (1.00, 1.61)		1.30 (0.92, 1.84)
Age at menarche
Not early (≥12)	2,356	1.17 (0.89, 1.53)	0.43	1.25 (0.84, 1.87)	0.47
Early (<12)	668	1.43 (0.93, 2.21)		1.62 (0.92, 2.85)
Family history of breast cancer
1 affected sister or half-sister	1,957	1.30 (0.99, 1.71)	0.46	1.37 (0.93, 2.01)	0.88
≥2 affected 1st degree relatives	1,067	1.08 (0.72, 1.63)		1.29 (0.70, 2.39)

^aHazard ratios adjusted for race/ethnicity, participant’s highest educational attainment at baseline, age at menarche, body mass index (as a restricted cubic spline), menopausal status at baseline, interaction between body mass index and menopausal status, parity, duration of hormonal contraceptive use, hormone therapy use, smoking, alcohol use and age at first birth.