. 2012 Nov 21;177(2):142–151. doi: 10.1093/aje/kws200

Table 2.

Adjusted Relative Risks and 95% Confidence Intervals for Type I and Type II Endometrial Carcinoma in Relation to Hormonal and Reproductive Factors in the NIH-AARP Diet and Health Study, 1995–2006

	No. of Noncases	Subtypes
		Type I (n = 1,312)			Type II (n = 138)
		No.	RR^a	95% CI	No.	RR^a	95% CI
Age at menarche, years
<13	53,393	681	1	Referent	74	1	Referent
13–14	48,277	527	0.92	0.82, 1.03	55	0.84	0.59, 1.20
≥15	10,852	102	0.82	0.67, 1.01	8	0.53	0.25, 1.10
		P_{heterogeneity}^b = 0.22
Age at menopause, years
<45	12,110	101	1	Referent	12	1	Referent
45–49	28,674	271	1.20	0.96, 1.51	28	1.05	0.53, 2.07
50–54	49,660	590	1.45	1.17, 1.79	64	1.32	0.71, 2.46
≥55	11,115	203	2.06	1.63, 2.63	16	1.40	0.66, 2.97
		P_{heterogeneity}^b = 0.40
Menopausal hormone therapy
Never user	67,831	787	1	Referent	93	1	Referent
Ever user	45,087	525	1.18	1.05, 1.32	45	0.84	0.57, 1.22
		P_{heterogeneity}^b = 0.01
Duration of MHT use, years
Never user	67,831	787	1	Referent	93	1	Referent
<5	22,549	183	0.81	0.69, 0.95	20	0.76	0.46, 1.25
5–9	13,336	160	1.23	1.03, 1.47	10	0.62	0.33, 1.22
≥10	9,072	182	2.09	1.77, 2.48	15	1.33	0.75, 2.36
		P_{heterogeneity}^b = 0.01
Oral contraceptive use
Never user	66,327	901	1	Referent	100	1	Referent
Ever user	45,792	405	0.73	0.64, 0.83	37	0.63	0.42, 0.95
		P_{heterogeneity}^b = 0.12
Duration of oral contraceptive use, years
Never user	66,327	901	1	Referent	100	1	Referent
1–4	19,885	176	0.74	0.62, 0.87	20	0.78	0.47, 1.29
5–9	14,197	142	0.83	0.69, 1.00	10	0.56	0.29, 1.10
≥10	11,710	87	0.61	0.49, 0.77	7	0.47	0.21, 1.02
		P_{heterogeneity}^b = 0.05
Parous
Nulliparous	19,717	302	1	Referent	31	1	Referent
Parous	92,745	1,002	0.69	0.60, 0.78	107	0.76	0.50, 1.14
		P_{heterogeneity}^b = 0.83
Age at first birth, years
Nulliparous	19,717	302	1	Referent	31	1	Referent
<20	15,441	164	0.69	0.56, 0.83	18	0.72	0.40, 1.30
20–<25	46,930	513	0.70	0.60, 0.81	59	0.82	0.53, 1.27
25–<30	22,186	254	0.74	0.62, 0.87	23	0.67	0.39, 1.15
≥30	8,180	76	0.61	0.47, 0.78	7	0.54	0.24, 1.23
		P_{heterogeneity}^b = 0.43
Parity, no. of previous births
Nulliparous	19,717	302	1	Referent	31	1	Referent
1	12,254	139	0.78	0.64, 0.95	13	0.71	0.37, 1.36
2	29,626	330	0.75	0.64, 0.88	37	0.85	0.53, 1.38
≥3	50,865	533	0.64	0.55, 0.73	57	0.68	0.43, 1.06
		P_{heterogeneity}^b = 0.86

Abbreviations: CI, confidence interval; MHT, menopausal hormone therapy; NIH, National Institutes of Health; RR, relative risk.

^a Adjusted for age (continuous), oral contraceptive use (ever/never), MHT use (ever/never), parity (nulliparous, 1, 2, ≥3 births), body mass index (<30 vs. ≥30 kg/m²), menarche (<13, 13–14, ≥15 years), age at menopause (premenopausal, <45, 45–49, 50–54, ≥55 years), race (white/nonwhite), and smoking status (never, former, current smoker). Unknown/missing was set as a separate category within each factor.

^b P value from logistic regression of case-only analysis comparing each risk factor.