Table 2 Patients’ demographic characteristics for SSI
Variable | Total (N = 554) | SSI (n = 19) | No-SSI (n = 535) | P value |
|---|---|---|---|---|
Preoperative baseline variables | ||||
 Age at surgery, mean (SD) | 56.9 (13.4) | 56.7 (16.0) | 56.9 (13.3) | 0.010 |
 BMI, mean (SD) | 24.1 (3.1) | 23.9 (3.9) | 24.1 (3.1) | 0.750 |
 Male | 237 (43) | 12 (63.2) | 225 (42.1) | 0.900 |
 Diabetes | 60 (10.8) | 2 (10.5) | 58 (10.8) | 0.300 |
 Smoker | 144 (26.0) | 6 (31.6) | 138 (25.8) | 0.235 |
 Chronic steroid use | 11 (1.99) | 5 (26.3) | 6 (1.1) | 0.003 |
 Albumin level < 3.5 g/dl | 13 (2.35) | 3 (15.8) | 10 (1.9) | 0.001 |
 Diagnose | ||||
  Herniation | 270 (48.7) | 6 (31.6) | 264 (49.3) | - |
  Stenosis | 86 (15.5) | 6 (31.6) | 80 (15.0) | 0.180 |
  Spondylolisthesis | 198 (35.7) | 7 (36.8) | 191 (35.7) | 0.001 |
Operative variables | ||||
 Operative time, mean (SD), min | 160.8 (43.9) | 155.5 (48.2) | 161.0 (43.8) | 0.178 |
 Bleeding volume, mean (SD) mL | 318.5 (90.8) | 321.1 (105.7) | 311.9 (89.2) | 0.537 |
Postoperative variables | ||||
 Albumin level < 3.5 g/dl | 314 (56.7) | 16 (84.2) | 298 (55.7) | < 0.001 |
 Albumin level < 3.0 g/dl | 110 (19.9) | 10 (52.6) | 100 (18.7) | < 0.001 |
 Postoperative drainage median, ml, (IQR) | 223.5 (151.0–309.0) | 148 (93.0-188.0) | 231 (154.0–312.0) | 0.116 |
 Length of stay, day, median, thousand CNY (SD) | 11.0 (9.0–14.0) | 22.0 (14.0–32.0) | 11.0 (9.0–14.0) | < 0.001 |
 Hospitalization expenses mean (SD) | 25.6 (8.7) | 43.9 (21.3) | 24.9 (7.2) | < 0.001 |