Table 1. Baseline characteristics of the patient population after multiple imputation of missing values and univariate association between variables and the risk of drain-related meningitis.
| Overall | No DRM | DRM | p-value* | |
| Median (IQR) or n (%) | n = 537 | n = 455 | n = 82 | |
| Demographics | ||||
| Age (years) | 58.5 (47.2–69.6) | 59.3 (46.8–69.4) | 56.0 (47.5–65.6) | 0.49 |
| Sex (% female) | 290 (54.0) | 247 (54.3) | 43 (52.4) | 0.78 |
| In-hospital death (%) | 90 (16.8) | 79 (17.4) | 11 (13.4) | 0.38 |
| Duration of admission (days) | 21.0 (12.0–37.5) | 19.0 (11.0–30.0) | 40.0 (28.5–59.3) | <0.001 |
| Admission on ICU (%) | 312 (58.1) | 253 (55.6) | 59 (72.0) | 0.006 |
| Duration of ICU stay | 2 (0.0–7.0) | 2 (0.0–5.0) | 4.5 (0.0–12.3) | <0.001 |
| Indication for first drain (%) | <0.001 | |||
| - SAH/IVH | 249 (46.4) | 205 (42.0) | 58 (70.7) | |
| - Infarction | 14 (2.6) | 14 (3.1) | 0 (0) | |
| - CSF leakage | 85 (15.8) | 77 (16.9) | 8 (9.8) | |
| - Perioperative | 86 (16.0) | 84 (18.5) | 2 (2.4) | |
| - Trauma | 14 (2.6) | 11 (2.4) | 3 (3.7) | |
| - Tumor | 37 (6.9) | 30 (6.6) | 7 (8.5) | |
| - Other | 52 (9.7) | 48 (10.5) | 4 (4.9) | |
| Drain characteristics | ||||
| Drain type (% EVD) | 337 (62.8) | 266 (58.5) | 71 (86.6) | <0.001 |
| Total drain duration (days) | 9.0 (6.0–17.0) | 8.0 (5.0–13.0) | 20.0 (15.0–29.8) | <0.001 |
| Number of drains placed | 1 (1 - 1) | 1 (1 - 1) | 2 (1–2) | <0.001 |
| Laboratory measures (blood) | ||||
| CRP (mg/L) | 96 (39–173) | 85 (32–165) | 141 (95–190) | <0.001 |
| Leukocytes (×109/L) | 15.7 (11.8–20.1) | 14.8 (11.3–19.0) | 20.1 (16.3–23.6) | <0.001 |
| Haemoglobin (mmol/L) | 6.6 (5.7–7.5) | 6.8 (5.8–7.6) | 6.0 (5.2–6.8) | <0.001 |
| Thrombocytes (×109/L) | 351 (262–495) | 329 (252–452) | 540 (381–714) | <0.001 |
| Laboratory measures (CSF) | ||||
| Leukocytes (×100/uL) | 1.9 (0.3–5.7) | 1.4 (0.2–4.3) | 10.4 (2.5–53.1) | <0.001 |
| Erythrocytes (×10000/uL) | 1.6 (0.2–7.4) | 1.2 (0.2–6.9) | 2.4 (0.8–10.6) | 0.006 |
| Binary leukocytes (%) | 152 (28.3) | 91 (20.0) | 61 (74.4) | <0.001 |
| Percentage neutrophils | 51.7 (33.1–74.0) | 47.8 (31.3–66.0) | 85.0 (70.0–91.5) | <0.001 |
| Neutrophil count (×100/uL) | 0.8 (0.1–4.9) | 0.4 (0.0–2.3) | 6.3 (0.6–38.0) | <0.001 |
| Glucose (mmol/L) | 3.4 (2.7–4.1) | 3.5 (2.9–4.2) | 2.3 (1.1–3.3) | <0.001 |
| Total protein (g/L) | 1.7 (0.8–2.8) | 1.7 (0.8–2.7) | 1.8 (1.1–3.3) | 0.027 |
| Culture results | ||||
| CSF and/or drain culture (%) | 106 (19.7) | 45 (9.9) | 61 (74.4) | <0.001 |
| Antibiotic use | ||||
| Any antibiotics started >4 days (%) | 271 (50.5) | 193 (42.4) | 78 (95.1) | <0.001 |
| Any empiric antibiotic therapy (%) | 123 (22.9) | 61 (13.4) | 62 (75.6) | <0.001 |
| Number of antibiotic started | 1.0 (0–3) | 1 (0–2) | 4 (3–6) | <0.001 |
*: p-value using χ2, student's t or Mann-Whitney U test where appropriate.
Abbreviations: DRM – drain-related meningitis; IQR –interquartile range; ICU – intensive care unit; CSF - cerebrospinal fluid; EVD – external ventricular drain; HAI – Healthcare-associated infection; SAH – subarachnoid hemorrhage; IVH – intraventricular hemorrhage.
Number of missing values prior to imputation: Other HAI – 37.2%; CRP – 11.2%; Leukocytes (blood) – 8.4%; Hemoglobin – 6.1%; Thrombocytes – 11.2%; CSF leukocytes – 29.2%; CSF erythrocytes 29.1%; CSF glucose 30.7%; CSF protein 29.2%; Culture (CSF and/or drain) – 19.9%. All others: no missing values.