Table 1.

Baseline characteristics of women without prevalent CKD in the Mayo Clinic Cohort Study of Oophorectomy and Aging-2 from Olmsted County, Minnesota

CharacteristicaReferent, n=1644Bilateral Oophorectomy, n=1638
Age at oophorectomy, median (IQR)44 (40–47)44 (40–47)
Age at oophorectomy, yr, n (%)
 ≤451028 (63)1024 (63)
 46–49616 (37)614 (37)
Calendar year of oophorectomy, n (%)
 1988–1992317 (19)317 (19)
 1993–1997404 (25)406 (25)
 1998–2002549 (33)546 (33)
 2003–2007374 (23)369 (23)
Race, n (%)
 White1561 (95)1596 (97)
 Black29 (2)18 (1)
 Asian49 (3)18 (1)
 Other5 (0.3)6 (0.4)
Years of education, n (%)
 <931 (2)8 (0.5)
 9–12443 (27)517 (32)
 13–16858 (52)883 (54)
 >16277 (17)227 (14)
 Unknownb35 (2)3 (0.2)
Smoking status, n (%)
 Never949 (58)891 (54)
 Past377 (23)388 (24)
 Current318 (19)359 (22)
BMI, kg/m2, median (IQR)25.9 (22.7–30.4)27.2 (23.3–32.4)
BMI, kg/m2, n (%)
 <25.0697 (42)590 (36)
 25.0–29.9486 (30)477 (29)
 ≥30.0438 (27)571 (35)
 Unknownb23 (1)0 (0)
Hysterectomy, n (%)
 No1482 (90)24 (1)
 Before162 (10)156 (10)
 Concurrent with oophorectomy1458 (89)
Oophorectomy indication, n (%)c
 No ovarian indication968 (59)
 Benign condition670 (41)
Concurrent hysterectomy indication, n (%)d
 Cancer11 (0.7)
 Suspicion of cancer308 (19)
 Bleeding823 (50)
 Pain588 (36)
 Fibroids or polyps412 (25)
 Prolapse335 (20)
 Endometriosis200 (12)
 Other225 (14)
  • IQR, interquartile range; BMI, body mass index; —, not applicable.

  • a Women with prevalent CKD defined using eGFR were excluded from this table (nine referent women and 15 women who underwent bilateral oophorectomy).

  • b In the regression models used to derive inverse probability weights, women with unknown education were assigned to the ≤12-year group, and women with unknown BMIs were assigned to the <30-kg/m2 group.

  • c The indication was listed by the gynecologist in the medical record at the time of oophorectomy. Benign conditions include benign tumors, cyst, or endometriosis in either ovary. No ovarian indication includes women without a benign ovarian condition in either ovary. Historically, the terms “prophylactic,” “elective,” or “incidental” oophorectomy were used; however, we avoided these terms.

  • d The indication was listed by the gynecologist in the medical record at the time of hysterectomy. Each woman may have more than one indication recorded.