Table 1.
Baseline characteristics of the study groups
| Baseline characteristics | Vancomycin treated N = 81 |
Vancomycin untreated N = 375 |
Difference (p-value) |
|---|---|---|---|
| Age (years) | |||
| Median | 50 | 45 | 0.06 |
| IQR | 27 | 22 | |
| Sex no. (%) | |||
| Male | 47 (58.0) | 249 (66.4) | 0.19 |
| Female | 34 (42.0) | 126 (33.6) | |
| BMI (kg/m2) | |||
| Median | 29.7 | 29.4 | 0.52 |
| IQR | 8.4 | 7.2 | |
| Type of surgery no. (%) | |||
| Lumbar | 58 (72.0) | 285 (76.0) | < 0.01 |
| Thoracic | 5 (6.0) | 5 (1.0) | |
| Thoracolumbar | 15 (18.0) | 30 (8.0) | |
| Cervical | 3 (4.0) | 55 (15.0) | |
| Smoking history no. (%) | |||
| Never smokers | 60 (74.0) | 232 (62.0) | 0.12 |
| Current smokers | 19 (23.0) | 125 (33.3) | |
| Former smokers | 2 (3.0) | 18 (5.0) | |
| Diabetes mellitus no. (%) | 20 (25.0) | 64 (17.0) | 0.14 |
| Renal functions no. (%) | |||
| Normal | 79 (98.0) | 371 (99.0) | 0.28 |
| Abnormal | 2 (2.0) | 4 (1.0) | |
| Hypertension no. (%) | 29 (36.0) | 98 (26.0) | 0.10 |
| History of spinal infection no. (%) | 4 (5.0) | 3 (1.0) | 0.02 |
| History of spinal surgeries no. (%) | 19 (23.0) | 54 (14.0) | 0.06 |
| History of antibiotic use within 90 days before index date no. (%) | 13 (16.0) | 28 (8.0) | 0.03 |
| Prolonged operation time no. (%) | 71 (88.0) | 29 (8.0) | < 0.01 |
| Surgical approach no. (%) | |||
| Anterior | 0 (0.0) | 31 (8.0) | < 0.01 |
| Posterior | 81 (100.0) | 344 (92.0) | |
| Implant no. (%) | 72 (89.0) | 184 (49.0) | < 0.01 |
| Alcohol as disinfectant no. (%) | 70 (86.0) | 303 (81.0) | 0.30 |
| Prophylactic gentamicin solution for irrigation no. (%) | 68 (84.0) | 281 (75.0) | 0.11 |
| Pre-operative white blood cell counts (in 10^3/µl) | |||
| Median | 7.5 | 8.2 | 0.08 |
| IQR | 3.8 | 3.1 | |
| Pre-operative neutrophil counts (%) | |||
| Median | 54.7 | 57.4 | 0.13 |
| IQR | 13.9 | 13.9 | |