Cases manually reclassified into symptom groups based on National Institute for Health and Care Excellence 2005 and 2015 referral criteria and their association with central nervous system cancer
| Referral criteria | Frequency, n (%) | CNS cancer, n | PPV, % (95% CI) | NPV, % (95% CI) |
|---|---|---|---|---|
| 2005 criteria | ||||
| Symptoms related to the CNS | 135 (88.2) | 4 | 3.0 (2.8–3.1) | 100.0 |
| New onset headaches becoming progressively severe or with features of raised ICP | 94 (61.4) | 2 | 2.1 (0.8–5.5) | 96.6 (91.3–98.7) |
| Subacute focal or non-focal neurological deficit | 63 (41.2) | 2 | 3.2 (1.2–8.2) | 97.8 (94.2–99.2) |
| Suspected recent-onset seizures | 14 (9.2) | 0 | 0.0 | 97.1 (97.0–97.2) |
| Behavioural and cognitive symptoms | 19 (12.4) | 1 | 5.3 (1.0–24.3) | 97.8 (96.1–98.7) |
| 2015 criteria | ||||
| Progressive, sub-acute loss of central neurological function | 20 (13.7) | 0 | 0.0 | 97.0 (96.8–97.2) |
CNS = central nervous system; ICP = intracranial pressure; NPV = negative predictive value; PPV = positive predictive value.