It is amazing the power of numbers to predict, and our inability to accurately judge risk. The CHADS Score predicts the risk of stroke on a yearly basis, depending on the number of risk factors you have. Most people understand that risk calcultion, but more worrisome is the likelihood of the event occuring given time. I have calculated 1 year risk, but then also placed the 5, 10, 15 and 20 year risk for stroke using the same estimated frequency. I think that many people would make different choices about anticoagulation if they recognized the cumulative risk.
| CHADS2 Score | Stroke Risk % | Year 1 | Year 5 | Year 10 | Year 15 | Year 20 |
| 0.0 | 1.9 | 1.9 | 9.1 | 17.5 | 25.0 | 31.9 |
| 1.0 | 2.8 | 2.8 | 13.2 | 24.7 | 34.7 | 43.3 |
| 2.0 | 4.0 | 4.0 | 18.5 | 33.5 | 45.8 | 55.8 |
| 3.0 | 5.9 | 5.9 | 26.2 | 45.6 | 59.8 | 70.4 |
| 4.0 | 8.5 | 8.5 | 35.9 | 58.9 | 73.6 | 83.1 |
| 5.0 | 12.5 | 12.5 | 48.7 | 73.7 | 86.5 | 93.1 |
| 6.0 | 18.2 | 18.2 | 63.4 | 86.6 | 95.1 | 98.2 |
Another way of presenting that same data is, if you have two of the CHADS risk factors for stroke, you have a 18.5% risk for stroke in the next 5 years and a 33.5% risk in the next 10 years. I think that would help guide the decision to take Coumadin, which is the standard recommendation if you have a CHADS score of 2.