Table 5.

Multivariable-adjusted^a hazard ratios (HR) and 95% confidence intervals for endometrial cancer in relation to estrogen (E) and progestin (P) average dose and potency in the Nurses’ Health Study II (1989–2017)

	Person-years	Cases	Including never OC users		Restricted to ever OC users
			HR	95% CI	HR	95% CI
E average dose
Never OC use	344,113	175	1.00	(ref.)	–	–
E dose < median	1,363,352	439	0.77	(0.64–0.92)	1.00	(ref.)
E dose ≥ median	211,119	113	0.80	(0.62–1.02)	1.03	(0.83–1.28)
P average dose
Never OC use	344,113	175	1.00	(ref.)	–	–
P dose < median	817,980	246	0.75	(0.61–0.91)	1.00	(ref.)
P dose ≥ median	764,521	312	0.80	(0.66–0.97)	1.07	(0.90–1.26)
E and P average dose
Never OC use	344,113	175	1.00	(ref.)	–	–
Both E and P doses < median	788,189	221	0.71	(0.58–0.87)	1.00	(ref.)
E dose < and P dose ≥ median	575,164	218	0.83	(0.68–1.02)	1.17	(0.97–1.41)
E dose ≥ and P dose < median	23,219	19	1.26	(0.78–2.03)	1.76	(1.09–2.84)
Both E and P doses ≥ median	187,900	94	0.74	(0.57–0.96)	1.04	(0.81–1.34)
p-het				0.03		0.01
E average potency
Never OC use	344,113	175	1.00	(ref.)	–	–
E potency < median	744,667	223	0.76	(0.62–0.94)	1.00	(ref.)
E potency ≥ median	700,808	258	0.74	(0.61–0.90)	0.97	(0.81–1.16)
P average potency
Never OC use	344,113	175	1.00	(ref.)	–	–
P potency < median	887,756	242	0.75	(0.61–0.91)	1.00	(ref.)
P potency ≥ median	565,585	245	0.77	(0.63–0.94)	1.03	(0.85–1.23)
E and P average potency
Never OC use	344,113	175	1.00	(ref.)	–	–
Both E and P potencies < median	519,934	148	0.78	(0.62–0.97)	1.00	(ref.)
E potency < and P potency ≥ median	224,904	75	0.74	(0.56–0.98)	0.96	(0.72–1.27)
E potency ≥ and P potency < median	361,709	88	0.68	(0.52–0.88)	0.87	(0.67–1.13)
Both E and P potencies ≥ median	339,099	170	0.78	(0.63–0.97)	1.01	(0.80–1.27)
p-het				0.26		0.95

^aAdjusted for age (months), calendar period, BMI (kg/m², continuous), number of full-term pregnancies (continuous), smoking status (never/past/current), menopausal status (premenopausal/postmenopausal/perimenopausal or unknown), use of HT (never/ever), diagnosis of PCOS (yes/no), laparoscopically confirmed endometriosis (yes/no), age of menarche (years), and use of IUD/diaphragm (yes/no).