Table 1. Subject characteristics.
| Case patients with first MI after breast cancer (n=134) | Controls without MI (n=262) | |
|---|---|---|
| Characteristic | N (%) | N (%) |
| Age at breast cancer diagnosis (years) | ||
| <50 | 10 (7.5) | 16 (6.1) |
| 50–59 | 23 (17.2) | 48 (18.3) |
| 60–69 | 46 (34.3) | 91 (34.7) |
| 70–79 | 42 (31.3) | 86 (32.8) |
| ⩾80 | 13 (9.7) | 21 (8.0) |
| Year of breast cancer diagnosis | ||
| 1980–1984 | 40 (29.9) | 75 (28.6) |
| 1985–1989 | 49 (36.6) | 96 (36.6) |
| 1990–1994 | 27 (20.2) | 59 (22.5) |
| 1995–1998 | 18 (13.4) | 32 (12.2) |
| Years between initial breast cancer and MI diagnoses a | ||
| <1 | 22 (16.4) | 42 (16.0) |
| 1–3 | 34 (25.4) | 69 (26.3) |
| 4–6 | 26 (19.4) | 52 (19.9) |
| 7–9 | 17 (12.7) | 32 (12.2) |
| ⩾10 | 35 (26.1) | 67 (25.6) |
| MI classification | ||
| Definite | 72 (53.7) | Not applicable |
| Probable | 22 (16.4) | |
| Immediate fatalityb | 40 (29.9) | |
a
As control subjects had no MI, data are from the reference date that marks the end of control subjects' at-risk period, which began at control subjects' dates of breast cancer diagnosis and extended for the duration of the matched case patients' time from breast cancer to MI diagnoses.
b
Cases identified from death certificate only; no diagnostic work-up to permit classification.