Table 1.
Association between potential risk factors and surgical site infection (SSI) in elective foot and ankle surgery
| Variables | Number (%) of infection | Number (%) of non-infection | p value |
|---|---|---|---|
| Gender (male) | 13 (50.0) | 576 (46.7) | 0.740 |
| Age (years) | 40.3 ± 11.5 | 45.3 ± 16.4 | 0.040 |
| Living place | 0.311 | ||
| Rural | 16 (61.5) | 635 (51.5) | |
| Urban | 10 (38.5) | 598 (48.5) | |
| BMI (kg/m2) | 24.4 ± 5.6 | 25.4 ± 3.9 | 0.280 |
| 18.5–23.9 | 8 (30.8) | 437 (35. 5) | 0.112 |
| < 18.5 | 3 (11.5) | 38 (3.1) | |
| 24.0–27.9 | 7 (26.9) | 472 (38.3) | |
| 28.0–31.9 | 6 (23.1) | 232 (18.8) | |
| ≥ 32.0 | 2 (7.7) | 54 (4.4) | |
| Diabetes mellitus | 7 (26.9) | 96 (7.8) | < 0.001 |
| Hypertension | 4 (15.4) | 259 (21.0) | 0.621 |
| Chronic heart disease | 3 (11.5) | 62 (5.0) | 0.138 |
| Allergy history | 2 (7.7) | 132 (10.7) | 0.622 |
| Preoperative stay (days) | 5.4 ± 3.4 | 2.8 ± 2.9 | < 0.001 |
| Total hospital stay (days) | 26.2 ± 10.4 | 10.3 ± 11.9 | < 0.001 |
| Intraoperative bleeding (mL) | 45.6 ± 83.2 | 71.8 ± 140.1 | 0.006 |
| Surgical duration (min) | 76.5 ± 47.0 | 64.8 ± 51.4 | 0.074 |
| Cigarette smoking | 8 (30.8) | 218 (17.7) | 0.085 |
| Alcohol consumption | 5 (19.2) | 402 (32.6) | 0.149 |
| Surgeon level | 0.403 | ||
| Attending or resident | 5 (19.2) | 167 (13.5) | |
| Senior or vice senior | 21 (80.8) | 1066 (86.5) | |
| Surgical location | 0.233 | ||
| Forefoot | 22 (84.6) | 869 (69.0) | |
| Midfoot | 1 (3.8) | 97 (7.7) | |
| Hindfoot | 3 (11.5) | 293 (23.3) | |
| Procedure | 0.677 | ||
| Osteotomy | 9 (34.6) | 488 (39.6) | |
| Arthrodesis | 7 (26.9) | 385 (31.2) | |
| Soft tissue | 1 (3.8) | 62 (5.0) | |
| Combined two or three above | 9 (34.6) | 298 (24.2) | |
| Anesthesia | < 0.001 | ||
| Local | 6 (23.1) | 585 (47.4) | |
| Spinal | 12 (46.2) | 564 (45.7) | |
| General | 8 (30.8) | 84 (6.8) | |
| Type of bone graft | 0.002 | ||
| None | 21 (80.8) | 1150 (93.3) | |
| Autograft | 3 (11.5) | 68 (5.5) | |
| Allograft or bone substitute | 2 (7.7) | 15 (1.2) | |
| ASA class | 0.123 | ||
| I | 6 (23.1) | 520 (42.2) | |
| II | 18 (69.2) | 680 (55.2) | |
| III or greater | 2 (7.7) | 33 (2.7) | |
| Intraoperative antibiotics | 16 (61.5) | 791 (64.2) | 0.779 |
| Postoperative antibiotics | 17 (65.4) | 724 (58.7) | 0.494 |
| Drainage use | 19 (73.1) | 713 (57.8) | 0.119 |
| TP (< 60 g/L) | 2 (7.7) | 65 (5.3) | 0.229 |
| ALB (< 35 g/L) | 7 (26.9) | 18 (1.5) | < 0.001 |
| GLOB (> 40 g/L) | 4 (15.4) | 43 (3.5) | 0.002 |
| A/G (< 1.2) | 7 (26.9) | 64 (5.2) | < 0.001 |
| ALT (> 40 U/L) | 4 (15.6) | 62 (5.0) | 0.019 |
| AST (> 35 U/L) | 4 (15.4) | 47 (3.8) | 0.011 |
| ALP (> upper limit) | 2 (7.7) | 17 (1.4) | 0.020 |
| FBG (mmol/L) | 5.9 ± 2.8 | 5.3 ± 1.4 | 0.042 |
| WBC (> 10 × 109/L) | 3 (11.5) | 44 (3.6) | < 0.001 |
| NEUT (> 6.3 × 109/L) | 5 (19.2) | 59 (4.8) | < 0.001 |
| LYM (> 3.2 × 109/L) | 3 (11.5) | 86 (7.0) | 0.468 |
| RBC (< lower limit) | 12 (46.2) | 14 (53.8) | < 0.001 |
| HGB (< lower limit) | 16 (61.5) | 10 (38.5) | < 0.001 |
| HCT (< lower limit) | 4 (15.4) | 97 (7.9) | 0.163 |
| MCHC (< lower limit) | 4 (15.4) | 22 (84.6) | < 0.001 |
| PLT (< lower limit) | 2 (7.7) | 24 (92.3) | < 0.001 |
| PDW (< lower limit) | 3 (11.5) | 23 (88.5) | 0.034 |
RBC red blood cell, reference range: females 3.5–5.0/1012/L and males 4.0–5.5/1012/L; HGB hemoglobin, reference range: females 110–150 g/L and males 120–160 g/L; ALB albumin; FBG fasting blood glucose; ALP alkaline phosphatase, 50–135 u/L; HCT hematocrit, 40–50%; MCHC, mean corpuscular hemoglobin concentration, 316–354 g/L; WBC white blood cell; NEUT neutrophil; LYM lymphocyte; PLT platelet, 100–300 × 109/L; TP total protein; ALB albumin; GLOB globulin; PDW platelet distribution width, reference 12–18.1%