Table 4.
Risk of ischaemic stroke in patients aged ≥75 with atrial fibrillation who were not taking warfarin, by incremental score in risk schemes
| Score | Events/person years | Risk/100 person years (95% CI) |
|---|---|---|
| CHADS2 index | ||
| 0 | — | — |
| 1 | 7/505 | 1.39 (0.56 to 2.86) |
| 2 | 27/607 | 4.45 (2.95 to 6.41) |
| 3 | 13/248 | 5.24 (2.82 to 8.80) |
| 4 | 4/115 | 3.48 (0.96 to 8.67) |
| 5 | 3/36 | 8.57 (1.80 to 23.06) |
| 6 | 0/2 | 0 (0 to 84.19)* |
| CHA2DS2-VASc | ||
| 0 | — | — |
| 1 | — | — |
| 2 | 6/284 | 2.11 (0.77 to 4.60) |
| 3 | 10/529 | 1.89 (0.91 to 3.48) |
| 4 | 24/359 | 6.69 (4.28 to 9.95) |
| 5 | 8/197 | 4.06 (1.75 to 8.01) |
| 6 | 6/110 | 5.45 (2.00 to 11.87) |
| 7 | 0/ 31 | 0 (0 to 11.90)* |
| 8 | 0/5 | 0 (0 to 73.78)* |
| Rietbrock modified CHADS2 | ||
| 0 | — | — |
| 1 | — | — |
| 2 | — | — |
| 3 | — | — |
| 4 | 3/258 | 1.16 (0.24 to 3.40) |
| 5 | 14/492 | 2.84 (1.56 to 4.77) |
| 6 | 13/391 | 3.32 (1.77 to 5.69) |
| 7 | 8/189 | 4.23 (1.83 to 8.34) |
| 8 | 3/12 | 25.0 (5.16 to 73.06) |
| 9 | 0 | — |
| 10 | 4/27 | 14.81 (4.04 to 37.93) |
| 11 | 5/66 | 7.58 (2.46 to 17.68) |
| 12 | 3/46 | 6.52 (1.34 to 19.06) |
| 13 | 1/34 | 2.94 (0.07 to 16.39) |
*One sided 97.5% confidence interval.