| Clinical decision rule | Adults | Children | ||
|---|---|---|---|---|
| Likelihood ratio | Probability of appendicitis (%)* | Likelihood ratio | Probability of appendicitis (%)* | |
| Alvarado score | ||||
| High risk: score ≥ 7 | 3.4 | 87 | 4.2 | 67 |
| Moderate risk: score 4 to 6 | 0.42 | 45 | 0.27 | 12 |
| Low risk: score < 4 | 0.03 | 3.7 | 0.02 | 1.9 |
| Pediatric Appendicitis Score | ||||
| High risk: score ≥ 8 | NA | NA | 8.1 | 80 |
| Moderate risk: score 4 to 7 | NA | NA | 0.7 | 26 |
| Low risk: score < 4 | NA | NA | 0.13 | 6.0 |