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Table 3 Expected and observed number of breast cancer in test subcohort of China Kadoorie Biobank (CKB) and Shanghai Women’s Health Study (SWHS)

From: Development and external validation of a breast cancer absolute risk prediction model in Chinese population

  Test subcohort of CKB SWHS
E O E/O (95% CI) E O E/O (95% CI)
Overall 760 751 1.01 (0.94–1.09) 1320 1409 0.94 (0.89–0.99)
Age at enrollment, years
 < 50 372 357 1.04 (0.94–1.16) 735 688 1.07 (0.99–1.15)
 50–59 277 256 1.08 (0.96–1.23) 377 394 0.96 (0.87–1.06)
 ≥ 60 111 138 0.81 (0.68–0.96) 208 327 0.64 (0.57–0.71)
Residence
 Rural 351 267 1.31 (1.17–1.49) -- -- --
 Urban 409 484 0.85 (0.77–0.93) 1320 1409 0.94 (0.89–0.99)
Highest education
 Primary school or lower 333 299 1.11 (0.99–1.25) 143 195 0.73 (0.64–0.85)
 Middle school 218 212 1.03 (0.90–1.18) 487 503 0.97 (0.89–1.06)
 High school or higher 209 240 0.87 (0.77–0.99) 690 711 0.97 (0.90–1.05)
BMI, kg/m2
 < 18.5 21 17 1.21 (0.76–2.08) 34 38 0.90 (0.66–1.27)
 18.5–23.9 340 326 1.04 (0.94–1.17) 627 660 0.95 (0.88–1.03)
 24.0–27.9 282 282 1.00 (0.89–1.13) 477 512 0.93 (0.85–1.02)
 ≥ 28 117 126 0.93 (0.78–1.12) 181 199 0.91 (0.79–1.05)
Height, cm
 < 150.2 139 122 1.14 (0.96–1.38) 85 119 0.71 (0.59–0.86)
 150.2–154.1 172 151 1.14 (0.97–1.35) 185 199 0.93 (0.81–1.07)
 154.2–158.1 204 217 0.94 (0.82–1.08) 360 387 0.93 (0.84–1.03)
 ≥ 158.2 245 261 0.94 (0.83–1.06) 690 704 0.98 (0.91–1.06)
No. of first-degree relatives diagnosed with overall cancer
 0 607 573 1.06 (0.98–1.15) 926 1023 0.91 (0.85–0.96)
 1 126 144 0.87 (0.74–1.04) 316 329 0.96 (0.86–1.07)
 ≥ 2 27 34 0.80 (0.57–1.16) 77 57 1.35 (1.04–1.78)
No. of live birth
 Nulliparous 14 12 1.17 (0.67–2.26) 52 58 0.89 (0.69–1.18)
 1 340 353 0.96 (0.87–1.07) 852 822 1.04 (0.97–1.11)
 ≥2 406 386 1.05 (0.95–1.17) 416 529 0.79 (0.72–0.86)
Age at menarche, years
 < 12 54 60 0.90 (0.70–1.19) 118 105 1.12 (0.93–1.37)
 13–14 244 266 0.92 (0.81–1.04) 556 567 0.98 (0.90–1.07)
 15–16 279 275 1.01 (0.90–1.15) 481 553 0.87 (0.80–0.95)
 ≥ 17 183 150 1.22 (1.04–1.45) 164 184 0.89 (0.77–1.04)
  1. Abbreviations: BMI body mass index, PY person-year, RR relative risk, CI confidence interval, E expected number of cases, O observed number of cases, -- not applicable