Table 1.
Characteristics of the Sample
| Control | Case | OR (95% CI) | ||
|---|---|---|---|---|
| (a) Demography adjustment factors | ||||
| Age at mammogram (y) | Median (IQR); OR per IQR in control participants | 59 (53–66) | 58 (51–65) | 0.90 (0.77–1.05) |
| Region (n, %) | Primary service vs outlying area | 1028/2243 (46%) | 146/474 (31%) | 1.90 (1.54–2.35) |
| Health Insurance (n, %) | Insured | 1528 (68%) | 257 (54%) | Reference |
| Medicaid | 660 (29%) | 198 (42%) | 1.78 (1.45–2.19) | |
| None | 55 (2%) | 19 (4%) | 2.05 (1.20–3.52) | |
| Financial screening (n, %) | Ever assessed vs never | 122/2243 (5%) | 73/474 (15%) | 3.16 (2.32–4.31) |
| Education (n, %) | Less* vs more education | 740/2243 (33%) | 231/474 (49%) | 1.93 (1.58–2.36) |
| Ethnicity (n, %) | Not white vs white | 207/2243 (9%) | 80/474 (17%) | 2.00 (1.51–2.64) |
| (b) Breast cancer risk factors | ||||
| Age at first child (y) | <20 | 246 (11.0%) | 68 (14.3%) | 0.85 (0.60–1.19) |
| 20–29 | 1212 (54.0%) | 248 (52.3%) | Reference | |
| 30+ | 325 (14.5%) | 57 (12.0%) | 1.13 (0.81–1.57) | |
| Nulliparous | 122 (5.4%) | 30 (6.3%) | 1.38 (0.89–2.14) | |
| Unknown | 338 (15.1%) | 71 (15.0%) | 1.19 (0.88–1.61) | |
| Menopausal status | Pre | 465 (20.7%) | 107 (22.6%) | Reference |
| Post | 1746 (77.8%) | 359 (75.7%) | 1.03 (0.72–1.47) | |
| Unknown | 32 (1.4%) | 8 (1.7%) | 1.02 (0.44–2.39) | |
| Affected first-degree relatives (n, %) | None | 1754 (78.3%) | 353 (74.8%) | Reference |
| 1 | 458 (20.4%) | 105 (22.2%) | 1.19 (0.92–1.52) | |
| 2+ | 29 (1.3%) | 14 (3.0%) | 2.48 (1.26–4.88) | |
| Age at menarche (y) | Median (IQR) | 13 (12–13) | 12 (12–13) | 0.92 (0.86–0.99) |
| Unknown (n, %) | 2 (<1%) | 1 (<1%) | ||
| Height (m) | Median (IQR) | 1.63 (1.60–1.68) | 1.63 (1.60–1.68) | 1.05 (0.94–1.18) |
| Unknown (n, %) | 0 (0%) | 0 (0%) | ||
| Body mass index (kg/m2) | Median (IQR) | 25.6 (22.6–29.9) | 27.5 (23.3–32.2) | 1.22 (1.08–1.37) |
| Unknown (n, %) | 0 (0%) | 0 (0%) | ||
| Tyrer-Cuzick risk (10y %) | Median (IQR) | 3.17 (2.35–4.56) | 3.29 (2.30–4.94) | 1.27 (1.14–1.40) |
Ref, reference category (OR = 1). *Less education includes “8th grade or less,” “Some high school,” “Completed high school,” and “Some college.”