Table 4 Multivariable-adjusted hazard ratios (95% CI) for associations of aspirin use and risk of breast cancer in the BWHS, overall and by ER status, stratified by selected risk factors, 1995–2017
From: Aspirin use and risk of breast cancer in African American women
| Â | Person-years | Cases | HR | 95% CI | Cases | HR | 95% CI | Cases | HR | 95% CI |
|---|---|---|---|---|---|---|---|---|---|---|
|  |  | All invasive (n = 1127) | ER-positive (n = 626) | ER-negative (n = 353) | ||||||
BMI < 30 kg/m2 | ||||||||||
 Non-use | 435,269 | 768 | 1.00 | Reference | 397 | 1.00 | Reference | 250 | 1.00 | Reference |
 Past use | 76,978 | 176 | 1.01 | 0.85, 1.21 | 113 | 1.10 | 0.87, 1.37 | 51 | 0.89 | 0.64, 1.23 |
 Current use | 77,740 | 183 | 0.92 | 0.77, 1.09 | 116 | 1.00 | 0.80, 1.25 | 52 | 0.84 | 0.61, 1.16 |
|  |  | All invasive (n = 792) | ER-positive (n = 446) | ER-negative (n = 216) | ||||||
BMI ≥ 30 kg/m2 | ||||||||||
 Non-use | 240,890 | 458 | 1.00 | Reference | 265 | 1.00 | Reference | 135 | 1.00 | Reference |
 Past use | 66,902 | 149 | 0.93 | 0.77, 1.13 | 94 | 0.89 | 0.70, 1.14 | 41 | 0.97 | 0.67, 1.38 |
 Current use | 72,411 | 185 | 0.91 | 0.76, 1.09 | 127 | 0.96 | 0.76, 1.20 | 40 | 0.77 | 0.53, 1.12 |
|  |  | All invasive (n = 947) | ER-positive (n = 532) | ER-negative (n = 288) | ||||||
WHR < 0.85 | ||||||||||
 Non-use | 358,866 | 635 | 1.00 | Reference | 336 | 1.00 | Reference | 201 | 1.00 | Reference |
 Past use | 60,791 | 136 | 0.98 | 0.80, 1.19 | 82 | 0.97 | 0.75, 1.25 | 41 | 0.91 | 0.64, 1.30 |
 Current use | 69,650 | 176 | 0.98 | 0.82, 1.17 | 114 | 1.07 | 0.85, 1.34 | 46 | 0.84 | 0.60, 1.19 |
|  |  | All invasive (n = 459) | ER-positive (n = 259) | ER-negative (n = 146) | ||||||
WHR ≥ 0.85 | ||||||||||
 Non-use | 137,202 | 273 | 1.00 | Reference | 145 | 1.00 | Reference | 87 | 1.00 | Reference |
 Past use | 36,330 | 96 | 1.04 | 0.81, 1.33 | 60 | 1.00 | 0.73, 1.38 | 31 | 1.15 | 0.74, 1.77 |
 Current use | 40,529 | 90 | 0.71 | 0.55, 0.92 | 54 | 0.67 | 0.48, 0.93 | 28 | 0.81 | 0.51, 1.28 |
|  |  | All invasive (n = 710) | ER-positive (n = 370) | ER-negative (n = 226) | ||||||
Premenopausal | ||||||||||
 Non-use | 436,127 | 577 | 1.00 | Reference | 290 | 1.00 | Reference | 185 | 1.00 | Reference |
 Past use | 52,186 | 76 | 1.01 | 0.79, 1.29 | 46 | 1.05 | 0.76, 1.46 | 26 | 1.02 | 0.67, 1.56 |
 Current use | 42,230 | 57 | 0.84 | 0.64, 1.11 | 34 | 0.95 | 0.66, 1.36 | 15 | 0.67 | 0.39, 1.15 |
|  |  | All invasive (n = 966) | ER-positive (n = 610) | ER-negative (n = 261) | ||||||
Postmenopausal | ||||||||||
 Non-use | 164,576 | 481 | 1.00 | Reference | 285 | 1.00 | Reference | 139 | 1.00 | Reference |
 Past use | 71,966 | 212 | 0.97 | 0.82, 1.16 | 139 | 0.96 | 0.77, 1.19 | 55 | 0.95 | 0.68, 1.32 |
 Current use | 93,480 | 273 | 0.91 | 0.78, 1.06 | 186 | 0.95 | 0.78, 1.15 | 67 | 0.87 | 0.64, 1.18 |
|  |  | All invasive (n = 766) | ER-positive (n = 385) | ER-negative (n = 249) | ||||||
Age < 50 | ||||||||||
 Non-use | 476,929 | 620 | 1.00 | Reference | 305 | 1.00 | Reference | 200 | 1.00 | Reference |
 Past use | 59,268 | 79 | 0.97 | 0.76, 1.24 | 44 | 0.96 | 0.69, 1.33 | 28 | 1.03 | 0.63, 1.55 |
 Current use | 45,174 | 67 | 0.98 | 0.76, 1.27 | 36 | 1.06 | 0.75, 1.51 | 21 | 0.95 | 0.60, 1.49 |
|  |  | All invasive (n = 1153) | ER-positive (n = 727) | ER-negative (n = 320) | ||||||
Age ≥ 50 | ||||||||||
 Non-use | 199,229 | 606 | 1.00 | Reference | 357 | 1.00 | Reference | 185 | 1.00 | Reference |
 Past use | 84,612 | 246 | 0.96 | 0.82, 1.12 | 163 | 0.98 | 0.81, 1.20 | 64 | 0.85 | 0.63, 1.15 |
 Current use | 104,977 | 301 | 0.89 | 0.77, 1.03 | 207 | 0.96 | 0.80, 1.15 | 71 | 0.76 | 0.57, 1.01 |
|  |  | All invasive (n = 405) | ER-positive (n = 246) | ER-negative (n = 103) | ||||||
Nulliparous | ||||||||||
 Non-use | 207,423 | 275 | 1.00 | Reference | 155 | 1.00 | Reference | 75 | 1.00 | Reference |
 Past use | 33,671 | 70 | 1.14 | 0.86, 1.51 | 54 | 1.31 | 0.94, 1.82 | 11 | 0.76 | 0.40, 1.46 |
 Current use | 31,741 | 60 | 0.87 | 0.64, 1.18 | 37 | 0.83 | 0.57, 1.22 | 17 | 1.11 | 0.63, 1.95 |
|  |  | All invasive (n = 659) | ER-positive (n = 388) | ER-negative (n = 202) | ||||||
Parous, breastfed | ||||||||||
 Non-use | 250,056 | 427 | 1.00 | Reference | 232 | 1.00 | Reference | 141 | 1.00 | Reference |
 Past use | 62,547 | 108 | 0.97 | 0.77, 1.21 | 69 | 1.06 | 0.79, 1.41 | 31 | 0.82 | 0.54, 1.24 |
 Current use | 69,258 | 124 | 0.95 | 0.76, 1.18 | 87 | 1.18 | 0.90, 1.54 | 30 | 0.69 | 0.45, 1.05 |
|  |  | All invasive (n = 850) | ER-positive (n = 475) | ER-negative (n = 262) | ||||||
Parous, never breastfed | ||||||||||
 Non-use | 199,229 | 522 | 1.00 | Reference | 275 | 1.00 | Reference | 167 | 1.00 | Reference |
 Past use | 84,612 | 146 | 0.91 | 0.75, 1.11 | 83 | 0.79 | 0.61, 1.03 | 50 | 1.10 | 0.78, 1.55 |
 Current use | 104,977 | 182 | 0.91 | 0.76, 1.09 | 117 | 0.89 | 0.71, 1.13 | 45 | 0.84 | 0.59, 1.19 |