Table 1.
Association between potential risk factors and postoperative SSIs in elderly patients (n = 4818) undergoing elective orthopaedic surgery
| Variables | Number (%) of patients without SSI (n = 4744) | Number (%) of patients with SSI (n = 74) | P |
|---|---|---|---|
| Gender (male) | 2172 (45.8) | 31 (41.9) | 0.505 |
| Age | 69.7 ± 10.7 | 72.1 ± 13.5 | 0.082 |
| Living place (rural) | 2593 (54.7) | 42 (56.8) | 0.719 |
| BMI (kg/m2) | 0.159 | ||
| 18.5 to 23.9 | 2021 (42.6) | 26 (35.1) | |
| <18.5 | 273 (5.8) | 2 (2.7) | |
| 24.0 to 27.9 | 1478 (31.2) | 23 (31.1) | |
| 28.0 to 31.9 | 647 (13.6) | 14 (18.9) | |
| ≥32.0 | 325 (6.9) | 9 (12.2) | |
| Diabetes mellitus | 746 (15.7) | 23 (31.1) | 0.001 |
| Hypertension | 1064 (22.4) | 19 (25.7) | 0.507 |
| Cardiac disease | 622 (13.1) | 12 (16.2) | 0.433 |
| Chronic pulmonary disease | 438 (9.2) | 10 (13.5) | 0.208 |
| Chronic nephrosis | 274 (5.8) | 9 (12.2) | 0.020 |
| Chronic liver disease | 303 (6.4) | 8 (10.8) | 0.124 |
| Cerebrovascular disease | 793 (16.7) | 16 (21.6) | 0.263 |
| Rheumatic diseases | 573 (12.1) | 13 (17.6) | 0.152 |
| Chronic steroid use | 616 (13) | 18 (24.3) | 0.004 |
| History of previous operation at any site | 1276 (26.9) | 21 (28.4) | 0.776 |
| Current smoking | 759 (16) | 22 (29.7) | 0.001 |
| Alcohol consumption | 1023 (21.6) | 19 (25.7) | 0.394 |
| History of allergy to medications/food | 392 (8.3) | 8 (10.8) | 0.431 |
| Disease type | 0.202 | ||
| Degenerative disease | 3051 (64.3) | 39 (52.7) | |
| Osteopathy | 1009 (21.3) | 22 (29.7) | |
| Deformity | 402 (8.5) | 7 (9.5) | |
| Others | 282 (5.9) | 6 (8.1) | |
| Preoperative stay (d) | <0.001 | ||
| 1 to 2 | 3231 (68.1) | 31 (41.9) | |
| 3 to 7 | 1070 (22.6) | 24 (32.4) | |
| >7 | 443 (9.3) | 19 (25.7) | |
| ASA class | 0.003 | ||
| I‐II | 3587 (75.6) | 45 (60.8) | |
| III‐IV | 1157 (24.4) | 29 (39.2) | |
| Anaesthesia (general versus others) | 2439 (51.4) | 39 (52.7) | 0.826 |
| Solution to prepare the skin (alcohol versus others) | 3071 (64.7) | 36 (48.6) | 0.004 |
| Perioperative allogenic blood transfusion | 498 (10.5) | 13 (17.6) | 0.05 |
| Surgeon level (visiting and residents versus others) | 1776 (37.4) | 34 (45.9) | 0.134 |
| Surgical procedure | <0.001 | ||
| Hip replacement | 1657 (34.9) | 12 (16.2) | |
| Knee placement | 1017 (21.4) | 7 (9.5) | |
| Spinal arthrodesis ± instrumentation | 796 (16.8) | 31 (41.9) | |
| Laminectomy ± discectomy | 854 (18) | 15 (20.3) | |
| Others | 420 (8.9) | 9 (12.2) | |
| Intraoperative blood loss | |||
| Surgical duration > 75th percentile | 1176 (24.8) | 28 (37.8) | 0.010 |
| Postoperative antibiotics use | 4426 (93.3) | 67 (90.5) | 0.348 |
| Postoperative drainage use | 2817 (59.4) | 52 (70.3) | 0.058 |
| WBC (>10 × 109/L) | 872 (18.4) | 18 (24.3) | 0.191 |
| NEUT (>6.3 × 109/L) | 698 (14.7) | 16 (21.6) | 0.097 |
| LYM (109/L) | 0.051 | ||
| References (1.1‐3.2) | 4026 (84.9) | 57 (77) | |
| <1.8 | 351 (7.4) | 11 (14.9) | |
| >3.2 | 367 (7.7) | 6 (8.1) | |
| &RBC < lower limit (1012/L) | 793 (16.7) | 17 (23) | 0.153 |
| #HGB < lower limit (g/L) | 902 (19) | 21 (28.4) | 0.042 |
| PLT (109/L) | 0.082 | ||
| References (100‐300) | 3845 (81) | 53 (71.6) | |
| <100 | 527 (11.1) | 14 (18.9) | |
| >300 | 372 (7.8) | 7 (9.5) | |
| TP (<55 g/L) | 838 (17.7) | 16 (21.6) | 0.376 |
| ALB (<35 g/L) | 1043 (22) | 26 (35.1) | 0.007 |
| GLOB >30 g/L | 684 (14.4) | 13 (17.6) | 0.347 |
| FBG > 125 mg/dL | 527 (11.1) | 17 (23) | 0.001 |
Abbreviations: &RBC, red blood cell. reference range: female, 3.5 to 5.0/1012/L; males, 4.0 to 5.5/1012/L. #HGB, haemoglobin, reference range: females, 110 to 150 g/L; males, 120 to 160 g/L; WBC, white blood cell; NEUT, neutrophile; LYM, PLT, platelet; TP, total protein; ALB, albumin; GLOB, globulin; FBG, fasting blood glucose.