Diagnostic performance of CT (<6 hours from headache onset)
| Study | N | Sens (%) | 95% CI | Spec (%) | 95% CI | FNR (%) | 95% CI | FPR (%) | 95% CI |
| Perry et al 12 | 953 | 100 | 100 to 100 | 100 | 100 to 100 | 0.0 | 0.0 to 0.0 | 0.0 | 0.0 to 0.0 |
| Backes et al 32 | 135 | 100 | 100 to 100 | 100 | 100 to 100 | 0.0 | 0.0 to 0.0 | 0.0 | 0.0 to 0.0 |
| Valle Alonso et al 30 | 85 | 100 | 100 to 100 | 98.7 | 96.1 to 100 | 0.0 | 0.0 to 0.0 | 1.3 | 0.0 to 3.9 |
| Perry et al (reclassified)23 | 1204 | 97.2 | 94.2 to 100 | 100 | 100 to 100 | 2.8 | 0.0 to 5.8 | 0.0 | 0.0 to 0.0 |
| Pooled (n=4) | 2377 | 98.7 | 96.5 to 100 | 100 | 99.7 to 100 | 1.34 | 0.50 to 3.52 | 0.00 | 0.00 to 0.34 |
FNR, false negative rate; FPR, false positive rate; N, number; Sens, sensitivity; Spec, specificity.