Table 2.
Variables that predict increased LOS in hospital after primary unilateral total knee replacement, based on univariate and multivariate analysis
| Variable | OR (95% CI) | p Value | aOR (95% CI) | p Value | |
| Patient demographics | |||||
| Age (years) | <60 | REF | REF | ||
| 60–64 | 0.95 (0.66 to 1.37) | 0.78 | 1.08 (0.73 to 1.59) | 0.71 | |
| 65–69 | 1.37 (0.98 to 1.92) | 0.07 | 1.42 (0.98 to 2.06) | 0.06 | |
| >70 | 2.04 (1.51 to 2.75) | <0.001 | 1.94 (1.38 to 2.73) | <0.001 | |
| Race | Malay | 0.66 (0.42 to 1.03) | 0.07 | 0.53 (0.31 to 0.92) | 0.02 |
| Indian | 1.24 (0.82 to 1.87) | 0.32 | 1.34 (0.85 to 2.11) | 0.21 | |
| Others | 1.82 (1.09 to 3.04) | 0.02 | 1.49 (0.83 to 2.68) | 0.19 | |
| Chinese | REF | REF | |||
| Body mass index | <25 | REF | REF | ||
| 25–29.9 | 0.90 (0.71 to 1.15) | 0.41 | 1.02 (0.78 to 1.32) | 0.91 | |
| 30–34.9 | 0.76 (0.56 to 1.03) | 0.07 | 0.92 (0.65 to 1.28) | 0.61 | |
| ≥35 | 1.18 (0.78 to 1.78) | 0.43 | 1.56 (0.96 to 2.53) | 0.07 | |
| Gender | Male | REF | REF | ||
| Female | 1.15 (0.90 to 1.47) | 0.25 | 1.20 (0.89 to 1.63) | 0.23 | |
| Details of operation | |||||
| Type of anaesthesia | GA | REF | REF | ||
| RA | 0.76 (0.62 to 0.94) | 0.01 | 0.75 (0.59 to 0.95) | 0.02 | |
| Duration of operation (minutes) | ≤100 | REF | REF | ||
| >100 | 1.41 (1.09 to 1.84) | 0.01 | 1.37 (1.03 to 1.84) | 0.03 | |
| Perioperative blood transfusion (units) | None | REF | REF | ||
| 1 | 4.10 (2.61 to 6.45) | <0.001 | 2.12 (1.24 to 3.60) | 0.006 | |
| ≥2 | 13.01 (6.46 to 26.17) | <0.001 | 6.71 (3.14 to 14.33) | <0.001 | |
| Repeat operation within Hhospital stay | 25.48 (3.06 to 212.14) | 0.003 | 15.22 (1.38 to 167.59) | 0.03 | |
| Day of week of operation | Monday | 2.20 (1.54 to 3.13) | <0.001 | 2.38 (1.62 to 3.49) | <0.001 |
| Tuesday | 2.10 (1.51 to 2.93) | <0.001 | 2.42 (1.68 to 3.49) | <0.001 | |
| Wednesday | 1.93 (1.35 to 2.76) | <0.001 | 2.21 (1.50 to 3.24) | <0.001 | |
| Thursday | REF | REF | |||
| Friday | 2.14 (1.50 to 3.06) | <0.001 | 1.99 (1.35 to 2.94) | 0.001 | |
| Saturday | 1.38 (0.79 to 2.41) | 0.25 | 1.46 (0.80 to 2.67) | 0.22 | |
| Patient comorbidities | |||||
| Anaemia | None | REF | REF | ||
| Mild | 1.97 (1.53 to 2.53) | <0.001 | 1.71 (1.29 to 2.27) | <0.001 | |
| Moderate/severe | 3.22 (2.29 to 4.53) | <0.001 | 2.29 (1.54 to 3.39) | <0.001 | |
| DM on insulin | 1.55 (0.77 to 3.12) | 0.22 | 1.20 (0.53 to 2.76) | 0.66 | |
| Creatinine >2 mg/dL | 4.26 (1.68 to 10.78) | 0.002 | 2.35 (0.78 to 7.11) | 0.13 | |
| Previous CVA | 3.33 (1.84 to 6.01) | <0.001 | 2.89 (1.50 to 5.55) | 0.001 | |
| IHD | 1.92 (1.30 to 2.83) | 0.001 | 1.50 (0.95 to 2.36) | 0.08 | |
| CCF | 2.11 (0.79 to 5.66) | 0.14 | 1.19 (0.38 to 3.75) | 0.77 | |
| Smoking | 0.98 (0.69 to 1.39) | 0.90 | 1.15 (0.76 to 1.75) | 0.50 | |
| ASA-PS score | 1 | REF | REF | ||
| 2 | 1.19 (0.77 to 1.83) | 0.44 | 0.96 (0.61 to 1.52) | 0.86 | |
| 3 | 2.88 (1.68 to 4.92) | <0.001 | 1.40 (0.77 to 2.56) | 0.27 | |
aOR, adjusted OR; 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; REF, reference.