Table 4.

Odds Ratios for Invasive Epithelial Ovarian Cancer and Population Attributable Fractions for Selected Ovarian Cancer Risk Factors in African-American and White Women, North Carolina Ovarian Cancer Study, 1999–2008

	Whites					African Americans
	No. of Cases	No. of Controls	ORa	95% CI	AF	No. of Cases	No. of Controls	ORa	95% CI	AF
Tubal ligation
Yes	168	269	1.00	Referent	0.204	33	91	1.00	Referent	0.341
No	515	547	1.37	1.08, 1.73		71	81	2.00	1.15, 3.48
Body mass indexb
<30	494	611	1.00	Referent	0.030	42	86	1.00	Referent	0.209
≥30	183	205	1.12	0.89, 1.42		62	86	1.54	0.91, 2.62
Duration of oral contraceptive use, years
≥1	355	503	1.00	Referent	0.119	44	103	1.00	Referent	0.245
<1	328	313	1.33	1.06, 1.67		60	69	1.74	0.99, 3.05
Ever being pregnant
Yes	575	734	1.00	Referent	0.052	91	164	1.00	Referent	0.079
No	108	82	1.49	1.06 2.08		14	8	2.43	0.88, 6.73

Abbreviations: AF, attributable fraction; CI, confidence interval; OR, odds ratio.

^aAdjusted for all of the variables in the table, as well as age, age at menarche, family history of breast or ovarian cancer, and breastfeeding.

^bWeight (kg)/height (m)².