Table 2.
Overall relapse hazard ratios for 33,496 women <74 years old with breast cancer and using digoxin
| Digoxin-exposed | Person-years | Relapse, number | Hazard ratio (95% CI) | P-value1 | |
|---|---|---|---|---|---|
| All | Yes | 1,872 | 69 | 1.13 (0.88, 1.46) | 0.04 |
| No | 148,034 | 5,037 | 1.0 | ||
| Estrogen receptor status | |||||
| Positive | Yes | 1,524 | 55 | 1.15 (0.87, 1.52) | 0.03 |
| No | 111,485 | 3,456 | 1.0 | ||
| Negative | Yes | 280 | 10 | 0.93 (0.45, 1.90) | 0.94 |
| No | 30,256 | 1,345 | 1.0 | ||
| Unknown | Yes | 67 | 4 | 1.67 (0.49, 5.69) | 0.53 |
| No | 6,293 | 236 | 1.0 | ||
| Digoxin exposure with anti-estrogen treatment2 | |||||
| Tamoxifen | Yes | 353 | 26 | 1.04 (0.68, 1.60) | 0.36 |
| No | 23,742 | 1,431 | 1.0 | ||
| Aromatase inhibitors | Yes | 79 | 4 | 1.87 (0.46, 7.56) | 0.68 |
| No | 2,467 | 87 | 1.0 | ||
| Neither | Yes | 1,038 | 33 | 1.10 (0.75, 1.61) | 0.49 |
| No | 81,704 | 2,815 | 1.0 | ||
Risk compares patients (complete information only) using digoxin to those not using digoxin (referent) overall and by first and subsequent years after breast cancer diagnosis, by estrogen receptor status and allocated anti-estrogen treatment regimen. 1The P- value evaluates the overall digoxin effect on the hazard ratios for relapse, permitting different digoxin effects in the first year and later years of follow-up. 2Not presented are risks in subjects who switched between tamoxifen and aromatase inhibitors (that is, they were exposed to both at some time in their treatment) and those still in blinded protocols (exposure unknown).