Table 1.
Participant characteristics
| Variable | Primary breast cancer | No breast cancer | P‐value |
|---|---|---|---|
| n = 4,607 | n = 23,035 | ||
| Age at diagnosis (years) | |||
| Mean (SD) | 58.6 (9.1) | 58.6 (9.1) | 0.974 |
| 55–65 years | 3,714 (80.6) | 18,562 (80.6) | 0.934 |
| 66–80 years | 782 (17.0) | 3,897 (16.9) | |
| 81 years | 111 (2.4) | 576 (2.5) | |
| Income† | |||
| <1,249 | 1,391 (30.2) | 6,758 (29.3) | <0.001 |
| 1,249–21,899 | 1,389 (30.2) | 7,723 (33.5) | |
| ≥21,900 | 1,827 (39.7) | 8,554 (37.1) | |
| Urbanization‡ | |||
| I (1) | 1,628 (35.3) | 6,714 (29.2) | <0.001 |
| II (2 + 3) | 1,724 (37.4) | 8,738 (37.9) | |
| III (4 + 5) | 557 (12.1) | 3,119 (13.5) | |
| IV (6 + 7) | 207 (4.5) | 1,615 (7.0) | |
| Missing | 491 (10.7) | 2,849 (12.4) | |
| Charlson Comorbidity Index | |||
| Mean (SD) | 0.6 (1.5) | 0.2 (0.6) | <0.001 |
| >1 | 692 (15.0) | 977 (4.2) | <0.001 |
| History of hyperlipidemia | 477 (10.4) | 1,916 (8.3) | <0.001 |
| History of hypertension | 1,177 (25.6) | 4,893 (21.2) | <0.001 |
| History of cardiovascular disease | 301 (6.5) | 1,311 (5.7) | 0.026 |
| History of chronic kidney disease | 25 (0.5) | 133 (0.6) | 0.775 |
| History of cerebrovascular disease | 155 (3.4) | 630 (2.7) | 0.019 |
| Median follow‐up period, years (IQR) | 1.1 (0.2–2.7) | 6.9 (3.9–10.6) | <0.001 |
Data are presented as mean ± standard deviation (SD), number (percentage) or median (interquartile range [IQR]). †Patients were divided into three subgroups according to the 33.3 and 66.6 percentile of income. ‡Patients were divided into four subgroups according to the level of urbanization where they resided: I (1): highly urbanized cities; II (2 + 3): moderately urbanized cities plus boom towns; III (4 + 5): general cities and towns plus aging towns; IV (6 + 7): suburbanized cities and towns plus remote towns.