Demographics of patients with normal LOS (≤6 days) versus those with prolonged LOS (>6 days) after primary unilateral TKR
| Variable | LOS ≤6 days n=1933 | LOS >6 days n=461 | p Value | |
| Patient demographics | ||||
| Age: mean (SD) | 65.9 (8.0) | 69.2 (8.6) | <0.001 | |
| Race: n (%) | Chinese | 1628 (84.2) | 385 (83.5) | 0.02 |
| Malay | 148 (7.7) | 23 (5.0) | ||
| Indian | 106 (5.5) | 31 (6.7) | ||
| Others | 51 (2.6) | 22 (4.8) | ||
| Body mass index: n (%) | <25 | 555 (29.2) | 138 (31.8) | 0.16 |
| 25–29.9 | 812 (42.7) | 182 (41.9) | ||
| 30–34.9 | 410 (21.5) | 77 (17.7) | ||
| ≥35 | 126 (6.6) | 37 (8.5) | ||
| Gender: n (%) | Male | 477 (24.7) | 102 (22.1) | 0.25 |
| Female | 1456 (75.3) | 359 (77.9) | ||
| Details of operation | ||||
| Type of anaesthesia: n (%) | GA | 649 (33.6) | 184 (39.9) | 0.01 |
| RA | 1284 (66.4) | 277 (60.1) | ||
| Duration of operation: minutes (SD) | 79.6 (21.6) | 84.9 (27.5) | <0.001 | |
| Perioperative blood transfusion – n (%) | None | 1879 (97.2) | 394 (85.5) | <0.001 |
| one unit | 43 (2.2) | 37 (8.0) | ||
| ≥2 units | 11 (0.6) | 30 (6.5) | ||
| Repeat operation within hospital stay: n (%) | Yes | 1 (0.1) | 6 (1.3) | <0.001 |
| Day of week of operation: n (%) | Monday | 307 (15.9) | 90 (19.5) | <0.001 |
| Tuesday | 424 (21.9) | 119 (25.8) | ||
| Wednesday | 326 (16.9) | 84 (18.2) | ||
| Thursday | 472 (24.4) | 63 (13.7) | ||
| Friday | 301 (15.6) | 86 (18.7) | ||
| Saturday | 103 (5.3) | 19 (4.1) | ||
| Patient comorbidities | ||||
| Anaemia: n (%) | None | 1537 (79.5) | 290 (62.9) | <0.001 |
| Mild | 294 (15.2) | 109 (23.6) | ||
| Moderate/severe | 102 (5.3) | 62 (13.4) | ||
| DM on insulin: n (%) | Yes | 30 (1.6) | 11 (2.4) | 0.22 |
| Creatinine >2 mg/dL: n (%) | Yes | 9 (0.5) | 9 (2.0) | 0.001 |
| Previous CVA: n (%) | Yes | 26 (1.3) | 20 (4.3) | <0.001 |
| IHD: n (%) | Yes | 89 (4.6) | 39 (8.5) | 0.001 |
| CCF: n (%) | Yes | 12 (0.6) | 6 (1.3) | 0.128 |
| Smoking: n (%) | Yes | 184 (9.5) | 43 (9.3) | 0.90 |
| ASA-PS | 1 | 137 (7.1) | 26 (5.6) | <0.001 |
| 2 | 1699 (87.9) | 382 (82.9) | ||
| 3 | 97 (5.0) | 53 (11.5) | ||
ASA-PS, American Society of Anesthesiologist Physical Status ; CCF, congestive cardiac failure; CVA, cerebrovascular accidents; DM, diabetes mellitus; GA, general anaesthesia; IHD, ischaemic heart disease; LOS, length of stay; RA, regional anaesthesia; TKR, total knee replacement.