Table 2.
Baseline data on SSI and non-SSI of patients in the training cohort
| Characteristics | All cases of training sample | Non-SSI | SSI | P value |
|---|---|---|---|---|
| Number | 288 | 259 | 29 | |
| Age (years)a | 61.75 ± 9.82 | 61.44 ± 9.63 | 64.48 ± 11.24 | 0.114 |
| BMI (kg/m2)a | 24.68 ± 3.06 | 24.64 ± 3.00 | 25.00 ± 3.58 | 0.553 |
| Height (mm)a | 162.16 ± 7.59 | 162.10 ± 7.49 | 162.66 ± 8.54 | 0.712 |
| Weight (kg)a | 64.96 ± 9.63 | 64.82 ± 9.40 | 66.29 ± 11.64 | 0.435 |
| The total volume of drainage (mL)a | 310.12 ± 133.13 | 309.20 ± 133.21 | 318.31 ± 134.48 | 0.728 |
| The last volume of drainage (mL)a | 28.95 ± 18.56 | 28.29 ± 18.73 | 34.86 ± 16.08 | 0.071 |
| The duration of drainage (days)a | 5.84 ± 1.10 | 5.86 ± 1.08 | 5.59 ± 1.30 | 0.198 |
| Lengths of admission (days)a | 14.01 ± 4.24 | 13.96 ± 4.11 | 14.41 ± 5.35 | 0.587 |
| Albumin (g/L)a | 34.39 ± 3.27 | 34.40 ± 3.31 | 34.23 ± 2.97 | 0.787 |
| The highest CRP (mg/L)a | 38.95 ± 30.24 | 37.59 ± 28.49 | 51.12 ± 41.47 | 0.022 |
| The last CRP (mg/L)a | 22.85 ± 22.80 | 22.83 ± 22.69 | 23.06 ± 24.15 | 0.959 |
| The highest WBC count (109/L)a | 12.98 ± 3.41 | 12.93 ± 3.31 | 13.43 ± 4.24 | 0.456 |
| The last WBC count (109/L)a | 8.71 ± 2.94 | 8.71 ± 2.77 | 8.70 ± 4.26 | 0.986 |
| The highest ESR count (mm/h)a | 24.98 ± 18.29 | 24.31 ± 18.17 | 30.93 ± 18.58 | 0.064 |
| The last ESR count (mm/h)a | 22.94 ± 17.08 | 22.65 ± 17.18 | 25.52 ± 16.17 | 0.392 |
| Subcutaneous fat thickness (mm)a | 12.42 ± 5.94 | 12.08 ± 5.84 | 15.42 ± 6.13 | 0.004* |
| LPM fat infiltration (%)a | 28.07 ± 11.14 | 26.90 ± 10.57 | 38.50 ± 10.75 | < 0.001* |
| Genderb | 0.348 | |||
| Female | 138 (47.9%) | 127 (49.0%) | 11 (37.9%) | |
| Male | 150 (52.1%) | 132 (51.0%) | 18 (62.1%) | |
| Drinkingb | 0.643 | |||
| No | 242 (84.0%) | 219 (84.6%) | 23 (79.3%) | |
| Yes | 46 (16.0%) | 40 (15.4%) | 6 (20.7%) | |
| Physical work | 117 (40.6%) | 107 (41.3%) | 10 (34.5%) | |
| Others | 166 (57.6%) | 150 (57.9%) | 16 (55.2%) | |
| Educationb | 0.618 | |||
| Primary and secondary school | 266 (92.4%) | 239 (92.3%) | 27 (93.1%) | |
| High school | 7 (2.4%) | 7 (2.7%) | 0 (0.0%) | |
| College | 15 (5.2%) | 13 (5.0%) | 2 (6.9%) | |
| Maximum body temperature (°C)b | 0.247 | |||
| 36.5–38 | 206 (71.5%) | 182 (70.3%) | 24 (82.8%) | |
| 38–39 | 76 (26.4%) | 72 (27.8%) | 4 (13.8%) | |
| > 39 | 6 (2.1%) | 5 (1.9%) | 1 (3.4%) | |
| Surgery duration (h)b | < 0.001* | |||
| < 3 | 120 (41.7%) | 119 (45.9%) | 1 (3.4%) | |
| 3–4 | 119 (41.3%) | 110 (42.5%) | 9 (31.0%) | |
| ≥ 4 | 49 (17.0%) | 30 (11.6%) | 19 (65.5%) | |
| Postoperative prophylactic antibiotics (days)b | 0.873 | |||
| < 3 | 187 (64.9%) | 167 (64.5%) | 20 (69.0%) | |
| 3–7 | 64 (22.2%) | 58 (22.4%) | 6 (20.7%) | |
| ≥ 7 | 37 (12.8%) | 34 (13.1%) | 3 (10.3%) |
BMI body mass index; CRP C-reactive protein; WBC white blood cell; ESR erythrocyte sedimentation rate; LPM lumbar paraspinal (multifidus and erector spinae) muscles; and UTIs: urinary tract infections
*P < 0.05
*Statistically significant
aMean ± SD
bPercentage (%)