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. Author manuscript; available in PMC: 2019 Nov 1.
Published in final edited form as: Maturitas. 2018 Sep 14;117:64–77. doi: 10.1016/j.maturitas.2018.09.002

Table 2.

Case-control analyses stratified by age at oophorectomy (or index date; all indications).

Age ≤45 Years Age 46–49 Years
Characteristica Bilateral
Oophorectomy
(n=1,031)		 Control Women
(n=1,031)		 Adjusted
Odds Ratio
(95% Cl)b 		p Value Bilateral
Oophorectomy
(n=622)		 Control Women
(n=622)		 Adjusted
Odds Ratio
(95% Cl)b 		p Value
N % N % N % N %
Age at menarchec
 <12 102 10.6 81 9.7 1.00 (reference) -- 45 8.5 54 10.5 1.00 (reference) --
 12 350 36.3 262 31.5 1.11 (0.76, 1.61) 0.60 198 37.4 196 38.2 1.30(0.78,2.15) 0.31
 13 377 39.1 312 37.5 0.91 (0.62, 1.32) 0.62 195 36.9 176 34.3 1.30(0.80,2.12) 0.29
 >13 135 14.0 178 21.4 0.59 (0.39, 0.90) 0.01 91 17.2 87 17.0 1.30(0.75,2.24) 0.35
Oral contraceptive use (ever vs. never)d 481 46.7 633 61.4 0.54(0.45, 0.65) <0.001 360 57.9 367 59.0 0.91 (0.72, 1.16) 0.46
Years of oral contraceptive usec,e
 0 or <0.5 550 54.2 398 41.5 1.00 (reference) -- 262 46.1 255 43.0 1.00 (reference) --
 0.5–4.9 258 25.4 215 22.4 0.85(0.67, 1.07) 0.17 144 25.4 134 22.6 1.03(0.75, 1.42) 0.86
 ≥5.0 207 20.4 346 36.1 0.42 (0.33, 0.52) <0.001 162 28.5 204 34.4 0.72 (0.54, 0.96) 0.03
Gravidityc
 0d 182 17.7 151 14.6 1.00 (reference) -- 71 11.4 76 12.2 1.00 (reference) --
 1 118 11.4 117 11.3 0.84(0.60, 1.17) 0.30 46 7.4 62 10.0 0.79(0.48, 1.32) 0.37
 2 299 29.0 297 28.8 0.80(0.61, 1.06) 0.13 197 31.7 184 29.6 1.10(0.74, 1.63) 0.63
 ≥3 432 41.9 466 45.2 0.74(0.57, 0.96) 0.02 308 49.5 300 48.2 1.11 (0.76, 1.61) 0.59
Twin or multiple gestationd  22 2.1 19 1.8 1.14(0.61, 2.14) 0.67 20 3.2 14 2.3 1.36(0.68,2.72) 0.38
Pregnancy lossd 344 33.4 343 33.3 0.99(0.82, 1.20) 0.92 206 33.1 188 30.2 1.18(0.92, 1.50) 0.20
Induced abortiond, f 62 6.0 88 8.5 0.66 (0.46, 0.93) 0.02 30 4.8 30 4.8 1.03(0.61, 1.73) 0.93
Spontaneous abortion or still birthd 303 29.4 287 27.8 1.07(0.88, 1.30) 0.51 185 29.7 167 26.8 1.18(0.91, 1.52) 0.20
Parityc
 0d 224 21.7 185 17.9 1.00 (reference) -- 89 14.3 94 15.1 1.00 (reference) --
 1 140 13.6 142 13.8 0.82(0.60, 1.12) 0.21 54 8.7 74 11.9 0.78(0.49, 1.26) 0.32
 2 375 36.4 383 37.1 0.78(0.61, 1.01) 0.06 244 39.2 212 34.1 1.19(0.83, 1.70) 0.34
 ≥3 292 28.3 321 31.1 0.73 (0.56, 0.95) 0.02 235 37.8 242 38.9 1.04(0.73, 1.50) 0.81
Breast feeding 280 37.4 434 53.4 0.49 (0.38, 0.63) <0.001 213 46.2 221 47.2 1.02(0.76, 1.37) 0.88
Infertilityd 214 20.8 98 9.5 2.56(1.96, 3.34) <0.001 78 12.5 66 10.6 1.17(0.82, 1.65) 0.39
Fibrocystic breast diseased 1568 55.1 619 60.0 0.78 (0.64, 0.95) 0.01 515 82.8 509 81.8 1.04(0.78, 1.39) 0.81
Smoking statusc
 Neverd 544 52.8 611 59.3 1.00 (reference) -- 353 56.8 346 55.6 1.00 (reference) --
 Former 222 21.5 212 20.6 1.11 (0.89, 1.38) 0.37 171 27.5 165 26.5 0.99(0.75, 1.31) 0.96
 Current 265 25.7 208 20.2 1.29(1.02, 1.63) 0.04 98 15.8 111 17.8 0.87(0.63, 1.21) 0.41
Pack-yearsc,e
 0 544 53.0 611 60.3 1.00 (reference) -- 353 57.1 346 57.1 1.00 (reference) --
 0.1–5.9 104 10.1 115 11.4 0.99(0.74, 1.32) 0.93 76 12.3 52 8.6 1.38(0.92,2.05) 0.12
 ≥6.0 378 36.8 287 28.3 1.31 (1.07, 1.60) 0.008 189 30.6 208 34.3 0.91 (0.70, 1.18) 0.47
Height (cm)c,e
 <161.0 307 29.8 313 30.5 1.00 (reference) -- 202 32.5 216 34.8 1.00 (reference) --
 161.0–166.9 378 36.7 358 34.9 1.04(0.83, 1.30) 0.71 224 36.0 221 35.6 1.02(0.77, 1.34) 0.91
 ≥167.0 346 33.6 354 34.5 0.97(0.77, 1.21) 0.79 196 31.5 184 29.6 1.06(0.78, 1.42) 0.71
Weight (kg)c,e
 <64.0 315 30.6 376 36.7 1.00 (reference) -- 140 22.5 197 32.2 1.00 (reference) --
 64.0–78.9 331 32.1 350 34.2 1.11 (0.89, 1.39) 0.34 225 36.2 214 35.0 1.49(1.11,2.01) 0.008
 ≥79.0 385 37.3 298 29.1 1.42(1.14, 1.77) 0.002 257 41.3 201 32.8 1.93(1.41,2.63) <0.001
Body mass index (kg/m2)c
 <25.0 409 39.7 452 44.4 1.00 (reference) -- 187 30.1 248 40.6 1.00 (reference) --
 25.0–29.9 284 27.5 302 29.6 1.04(0.84, 1.29) 0.71 197 31.7 186 30.4 1.45(1.08, 1.94) 0.01
 >30.0 338 32.8 265 26.0 1.30(1.05, 1.61) 0.02 238 38.3 177 29.0 1.94(1.45,2.60) <0.001
a

Women with missing or unknown data were not included in the respective analysis for the following characteristics: 467 for age at menarche (67 cases age ≤45 and 198 controls; 93 cases age 46–49 and 109 controls), 171 for years of birth control use (16 cases age ≤45 and 72 controls; 54 cases age 46–49 and 29 controls), 817 for breast feeding status (283 cases age ≤45 and 219 controls; 161 cases age 46–49 and 154 controls), 43 for smoking pack-years (5 cases age ≤45 and 18 controls; 4 cases age 46–49 and 16 controls), and 23 women for height, weight and/or body mass index (0 cases age ≤45 and 12 controls; 0 cases age 46–49 and 11 controls).

b

The odds ratios and confidence intervals for each characteristic were calculated using conditional logistic regression models (matched pairs) adjusted for years of education (≤12; 13–16; >16), race (white; non-white) and quartiles of household income (<$42,000; $42,000–56,999; $57,000–71,999; ≥$72,000). Women with unknown education (2 cases age ≤45 and 23 controls; 1 case age 46–49 and 12 controls) were assigned to the ≤12 years group, and women with unknown income (5 cases age ≤45 and 2 controls; 1 case age 46–49 and 0 controls) were assigned to the $42,000–56,999 group (second quartile).

c

Ordinal characteristics were also tested for dose-effect (i.e., linear) trends adjusted for years of education, race, and household income: age at menarche (age ≤45 stratum p<0.001, age 46–49 stratum p=0.50), years of oral contraceptive use (age ≤45 stratum p<0.001, age 46–49 stratum p=0.03), gravidity (age ≤45 stratum p=0.03, age 46–49 stratum p=0.26), parity (age ≤45 stratum p=0.02, age 46–49 stratum p=0.41), smoking status (age ≤45 stratum p=0.03, age 46–49 stratum p=0.47), pack-years (age ≤45 stratum p=0.01, age 46–49 stratum p=0.54), height (age ≤45 stratum p=0.76, age 46–49 stratum p=0.72), weight (age ≤45 stratum p=0.002, age 46–49 stratum p<0.001), and body mass index (age ≤45 stratum p=0.02, age 46–49 stratum p<0.001).

d

For these characteristics, women with missing or unknown data were included in the no exposure category.

e

Years of oral contraceptive use, smoking pack-years, height, and weight were stratified using tertiles calculated from the overall sample (case-control groups pooled).

f

We may have underestimated induced abortions performed outside of the medical care facilities included in the REP.