Baseline data and univariate comparison between both groups
| Variables | SSI group (n = 18) | Non-SSI group (n = 450) | Statistical value | P value | OR | 95% CI | |
|---|---|---|---|---|---|---|---|
| Lower limit | Upper limit | ||||||
| Gender (male/female) | 5/13 | 242/208 | χ2 = 3.922 | 0.047** | 1.769 | 1.159 | 3.154 |
| Age (years,x̄ ± s) | 59.72 ± 7.19 | 56.34 ± 8.53 | t = 2.472 | 0.012*** | 2.106 | 1.267 | 4.171 |
| ASA score (e.g., I/II/III) | 9/7/2 | 192/238/20 | Z = -0.774 | 0.452** | 0.972 | 0.984 | 1.013 |
| BMI (kg/m2) | 23.92 ± 3.11 | 24.28 ± 3.21 | t = 0.054 | 0.955* | 1.001 | 0.998 | 1.005 |
| Preoperative comorbidities | |||||||
| cardiovascular or cerebrovascular disease (e.g., yes/no) | 2/16 | 33/417 | χ2 = 0.216 | 0.635* | 0.805 | 0.475 | 1.592 |
| Diabetes (e.g., yes/no) | 9/9 | 45/405 | χ2 = 24.705 | <0.001*** | 1.035 | 1.127 | 1.225 |
| Hypertension (e.g., yes/no) | 4/14 | 76/374 | χ2 = 0.060 | 0.805* | 1.168 | 1.117 | 1.692 |
| UTI (e.g., yes/no) | 7/11 | 29/421 | χ2 = 23.131 | <0.001*** | 1.006 | 1.002 | 1.021 |
| Preoperative albumin (g/L) | 36.12 ± 3.20 | 40.27 ± 3.08 | t = –2.739 | 0.018*** | 1.702 | 1.049 | 2.283 |
| Preoperative hemoglobin (g/L) | 134.27 ± 7.38 | 138.52 ± 8.59 | t = –3.658 | 0.008*** | 1.533 | 1.063 | 2.161 |
| Operated level (e.g., single level/multiple levels) | 5/13 | 289/161 | χ2 = 13.621 | <0.001*** | 1.701 | 1.129 | 2.147 |
| Operative time (min) | 206.37 ± 15.58 | 181.15 ± 13.12 | t = 8.515 | <0.001*** | 1.604 | 1.302 | 2.315 |
| Intraoperative blood loss (mL) | 262.24 ± 51.30 | 258.35 ± 49.06 | 0.320 | 0.731* | 1.157 | 1.078 | 1.703 |
| Intraoperative allogeneic blood transfusion (e.g., yes/no) | 2/16 | 45/405 | 0.047 | 0.825* | 1.021 | 1.019 | 1.475 |
| Post-operative drainage (mL) | 329.27 ± 53.69 | 291.52 ± 48.71 | 3.246 | 0.001*** | 1.005 | 1.035 | 1.081 |
| Post-operative draining time (d) | 2.41 ± 0.45 | 2.02 ± 0.41 | 4.145 | <0.001*** | 1.028 | 1.205 | 2.039 |
Multivariate logistic regression analysis results for early SSI after PLIF_
| Variables | Regression coefficient | Standard error | P value | OR | 95% CI | |
|---|---|---|---|---|---|---|
| Lower limit | Upper limit | |||||
| Gender | –0.235 | 0.163 | 0.027 | 0.736 | 0.437 | 1.285 |
| Preoperative diabetes | 0.778 | 0.315 | 0.012 | 2.109 | 1.175 | 3.866 |
| Preoperative UTI | 0.510 | 0.162 | 0.035 | 1.526 | 1.008 | 2.869 |
| Preoperative albumin | –0.602 | 0.276 | 0.004 | 0.526 | 0.317 | 0.925 |
| Time of draining | 0.539 | 0.175 | 0.029 | 1.639 | 1.196 | 3.053 |