Table 3.

Hazard Ratios of Hyperthyroidism/Hypothyroidism and Breast Cancer Risk in the Women's Health Initiative Cohorts by Ethnicity

Invasive breast cancer (No. of cases = 8137)
	Total No.	Cases	Model 1a	Model 2b
			HR [95% CI]	HR [95% CI]
Participants with history of hyperthyroidism
White (not of Hispanic origin)	1302	92	1.11 [0.90–1.36]	1.12 [0.90–1.38]
Black or African American	255	15	1.37 [0.82–2.29]	1.06 [0.56–1.98]
Hispanic/Latino	42	2	1.31 [0.32–5.28]	1.36 [0.33–5.54]
Asian or Pacific Islander	63	2	0.72 [0.18–2.92]	0.71 [0.17–2.86]
Other	33	3	1.83 [0.58–5.80]	1.67 [0.40–6.96]
Participants with history of hypothyroidism
White (not of Hispanic origin)	18,127	1107	0.95 [0.89–1.01]	0.89 [0.83–0.95]
Black or African American	643	32	1.15 [0.80–1.64]	1.13 [0.77–1.66]
Hispanic/Latino	442	23	1.55 [1.00–2.40]	1.50 [0.95–2.36]
Asian or Pacific Islander	261	16	1.40 [0.84–2.35]	1.35 [0.80–2.30]
Other	262	12	0.91 [0.50–1.68]	0.96 [0.51–1.80]

^aModel 1 is adjusted for age, cohort type (OS, CT).

^bModel 2 is adjusted for variables in Model 1 and for race/ethnicity, body mass index, smoking, alcohol intake, history and type of MHT, history of oophorectomy, parity history and numbers, age at menarche, age at menopause, family history of breast cancer, mammogram ever, breastfeeding, and breastfeeding duration.