Table 1 Demographic and clinical characteristics of the derivation and validation cohorts

Age at onset ≤ 60 years, n (%)

195 (87.8)

82 (82.0)

0.162

Male sex, n (%)

129 (58.1)

65 (65.0)

0.242

Duration of symptoms > 5 days, n (%)

113 (50.9)

54 (54.0)

0.607

Symptoms

 Headache, n (%)

215 (96.8)

89 (89.0)

0.005

 Fever, n (%)

202 (91.0)

86 (86.0)

0.177

 Vomiting, n (%)

152 (68.5)

60 (60.0)

0.138

 Nuchal rigidity, n (%)

145 (65.3)

66 (60.0)

0.905

 Convulsions, n (%)

29 (13.1)

12 (12.0)

0.791

 Disturbance of consciousness, n (%)

66 (29.7)

37 (37.0)

0.196

 Persistent cough > 2 weeks, n (%)

7 (3.2)

3 (3.0)

> 0.99

 Weight loss > 5% of the original weight within 6 months, n (%)

24 (10.8)

9 (9.0)

0.620

 Cranial nerve palsies, n (%)

4 (1.8)

7 (7.0)

0.041

 Focal neurologic deficit, n (%)

10 (4.5)

2 (2.0)

0.435

Concomitant diseases

 Cerebral infarction, n (%)

11 (5.0)

8 (8.0)

0.283

 Hydrocephalus, n (%)

13 (5.9)

11 (11.0)

0.104

 Extracranial tuberculosis, n (%)

37 (16.7)

22 (22.0)

0.252

 Hyponatremia < 135 mmol/L, n (%)

71 (32.0)

39 (39.0)

0.219

CSF alterations

 Intracranial pressure (> 180 mmH₂O), n (%)

172 (77.5)

69 (69.0)

0.105

 CSF cell count (> 500 × 10⁶ /L), n (%)

64 (28.8)

29 (29.0)

0.975

 CSF lymphocyte percentage (> 50%), n (%)

137 (61.7)

61 (61.0)

0.903

 CSF protein concentration (> 1 g/L), n (%)

153 (68.9)

72 (72.0)

0.577

 CSF glucose concentration (< 2.2 mmol/L), n (%)

103 (46.4)

49 (49.0)

0.665

 CSF chloride concentration (< 120 mmol/L), n (%)

151 (68.0)

60 (60.0)

0.161