Ability of the investigations to predict meningococcal infection
| Sensitivity | Specificity | PPV | NPV | |
|---|---|---|---|---|
| Variable | % | % | % | % |
| Abnormal white count | 58 (39 to 78) | 56 (48 to 63) | 14 (7 to 21) | 91 (84 to 99) |
| Abnormal neutrophil count | 68 (49 to 88) | 62 (55 to 69) | 17 (9 to 25) | 94 (87 to 100) |
| INR >1.2 | 58 (39 to 78) | 96 (92 to 99) | 67 (47 to 87) | 94 (88 to 100) |
| APTTR >1.18 | 9 (0 to 19) | 99 (98 to 100) | 67 (13 to 100) | 88 (82 to 94) |
| Platelets < 150×109/l | 25 (8 to 42) | 92 (88 to 96) | 30 (10 to 50) | 90 (84 to 96) |
| CRP > 6 mg/l | 100 (96 to 100) | 54 (47 to 62) | 18 (10 to 26) | 100 (92 to 100) |
95% CI in parentheses.
PPV, positive predictive value; NPV, negative predictive value.