Table 3.
Number Needed to Treat to Prevent a Single VTE Event by Caprini Score
| Caprini Score |
Event rate without pharmacologic prophylaxis |
Event rate with pharmacologic prophylaxis |
ARR (95% CI) | NNT |
|---|---|---|---|---|
| ≥1 | 1.13% | 1.04% | 0.08% (−0.08% to 0.26%) | 1179 |
| ≥2 | 1.21% | 1.08% | 0.13% (−0.05% to 0.31%) | 759 |
| ≥3 | 1.35% | 1.16% | 0.19% (−0.01% to 0.40%) | 519 |
| ≥4 | 1.48% | 1.29% | 0.20% (−0.04% to 0.44%) | 511 |
| ≥5 | 1.62% | 1.39% | 0.22% (−0.05% to 0.52%) | 447 |
| ≥6 | 1.69% | 1.50% | 0.19% (−0.14% to 0.54%) | 534 |
| ≥7 | 2.03% | 1.62% | 0.41% (−0.02% to 0.86%) | 247 |
| ≥8 | 2.03% | 1.53% | 0.50% (−0.06% to 1.06%) | 199 |
| ≥9 | 2.04% | 1.61% | 0.42% (−0.21% to 1.13%) | 237 |
| >10 | 2.15% | 1.78% | 0.37% (−0.49% to 1.23%) | 269 |
Abbreviations: VTE, venous thromboembolism; ARR, absolute risk reduction; NNT, number needed to treat, CI, confidence interval
As the 95% CIs for the ARR at each Caprini cut-point extends from a negative number (treatment may harm) to a positive number (treatment may benefit), there is uncertainty regarding benefit, harm, or lack of effect at all Caprini score values.