Table 2.
Exposure Variable | No. of Case Patients | No. of Control Participants | Adjusted Odds Ratioa | 95% Confidence Interval |
Tubal sterilization and another reproductive surgery | ||||
No reproductive surgery | 2,339 | 2,174 | 1.00 | Referent |
No tubal sterilization, but other reproductive surgeryb | 925 | 1,133 | 0.74 | 0.66, 0.83 |
Tubal sterilization | 1,226 | 1,304 | 0.93 | 0.84, 1.03 |
Plus hysterectomy or ovariectomy | 326 | 385 | 0.83 | 0.70, 0.99 |
Alone | 900 | 919 | 0.97 | 0.86, 1.09 |
Age at tubal sterilization, yearsc | ||||
<28 | 178 | 199 | 0.90 | 0.72, 1.12 |
28–31 | 203 | 208 | 0.99 | 0.80, 1.22 |
32–35 | 244 | 240 | 1.01 | 0.83, 1.22 |
≥36 | 275 | 272 | 0.97 | 0.81, 1.16 |
Calendar year of tubal sterilizationc | ||||
<1975 | 212 | 226 | 0.90 | 0.73, 1.10 |
1975–1979 | 216 | 223 | 0.92 | 0.75, 1.13 |
1980–1984 | 213 | 194 | 1.09 | 0.88, 1.34 |
≥1985 | 259 | 276 | 0.98 | 0.81, 1.18 |
Adjusted for age (continuous), race (white or black), study site (Atlanta, Detroit, Los Angeles, Philadelphia, or Seattle), age at menarche (continuous), first-degree family history of breast cancer (yes, no, or unknown/adopted), number of term pregnancies (0, 1, 2, or ≥3), educational status (some high school or less, high school graduate, some college or technical school, or college graduate or higher), and duration of hormone therapy use (never, 0–6 months, >6 months to <5 years, or ≥5 years).
Includes women with hysterectomy and/or ovariectomy.
Restricted to women who had a tubal sterilization without hysterectomy or ovariectomy.