| Characteristic | Nonserious intracranial headache (366 patients) | Serious intracranial headache (88 patients) | value |
| Age, years, median (IQR) | 54.5 (42, 70) | 51 (40, 64.2) | 0.157 | Male | 131 (35.8) | 41 (46.6) | 0.08 |
| Comorbidity | Diabetic mellitus | 42 (11.5) | 12 (13.6) | 0.705 | Hypertension | 118 (32.2) | 28 (31.8) | 1 | Hyperlipidemia | 84 (23) | 18 (20.5) | 0.718 | Atrial fibrillation | 12 (3.3) | 1 (1.1) | 0.478 | Ischemic heart disease | 17 (4.6) | 3 (3.4) | 0.777 | Cerebrovascular disease | 29 (7.9) | 8 (9.1) | 0.887 | HIV infection | 5 (1.4) | 7 (8) | 0.003 | Malignancy | 21 (5.7) | 14 (15.9) | 0.003 |
| Current medication | ASA | 46 (12.6) | 7 (8) | 0.305 | Clopidogrel | 3 (0.8) | 0 (0) | 1 | Anticoagulant | 11 (3) | 4 (4.5) | 0.505 | Prednisolone | 0 (0) | 2 (2.3) | 0.037 | Hormonal therapy | 1 (0.3) | 3 (3.4) | 0.024 |
| Clinical presentation | Gradual onset | 308 (84.2) | 55 (62.5) | <0.001 | Abrupt onset | 58 (15.8) | 33 (37.5) | <0.001 | Duration of headache >1 week | 34 (9.3) | 22 (25) | <0.001 | Occipital pain | 60 (16.4) | 21 (23.9) | 0.137 | Pain score | 7 (5, 8) | 10 (8, 10) | <0.001 | Awakening pain | 41 (11.2) | 42 (47.7) | <0.001 | Worst headache ever | 61 (16.7) | 77 (87.5) | <0.001 | Neck pain | 61 (16.7) | 29 (33) | <0.001 | Nausea/vomiting | 149 (40.7) | 57 (64.8) | <0.001 | Fever | 26 (7.1) | 22 (25) | <0.001 | Positional provocation | 5 (1.4) | 4 (4.5) | 0.076 | Seizure | 5 (1.4) | 7 (8) | 0.003 |
| Physical examination | BT, °C, median (IQR) | 36.6 (36.2, 36.9) | 36.8 (36.2, 37.3) | 0.008 | SBP, mmHg, median (IQR) | 144 (128, 161) | 140.5 (127, 162) | 0.621 | PR, bpm, median (IQR) | 76 (68, 88) | 77 (67.5, 88.2) | 0.89 | RR, breath/min, median (IQR) | 20 (20, 24) | 24 (20, 24) | 0.018 | SpO2, %, median (IQR) | 99 (98, 100) | 99 (97, 100) | 0.006 | Altered consciousness | 1 (0.3) | 6 (6.8) | <0.001 | Localizing neurological deficit | 13 (3.6) | 20 (22.7) | <0.001 | Stiffness of neck | 4 (1.1) | 15 (17) | <0.001 |
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