Table 2.
General linear model identifying predictors of knee pain and function 12-month after total knee replacement in the development dataset. OKS, Oxford knee score; IMD, index of multiple deprivation; BMI, body mass index; ASA grade, physical status scoring according to the American society of anaesthesiologists; ACL, anterior cruciate ligament; EQ-5D-3L, 3-level version of the EuroQol five dimensions questionnaire; CI, confidence interval. Variables included in the final regression model are those that are retained in at least 70% of the 200 bootstrap backward selection regression models.
| Intercept and Predictors (reference category) | Overall (n = 1,649) | ||
|---|---|---|---|
| % Retained in final model | Coefficient (95% CI) | P-value | |
| Intercept | 32.9 | ||
| Age at operation (<60 years) | |||
| 60–69 years | 100% (forced) | 0.8 (−1.5 to 3.1) | 0.477 |
| 70 to 79 years | 100% (forced) | 1.4 (−0.9 to 3.6) | 0.238 |
| 80 years or more | 100% (forced) | −2.5 (−5.5 to 0.4) | 0.088 |
| Gender (Female) | |||
| Male | 100% (forced) | −4.8 (−8.0 to −1.6) | 0.003 |
| Age x gender (<60 years x female) | |||
| 60–69 years x male | 90% | 4.8 (1.4 to 8.3) | 0.006 |
| 70 to 79 years x male | 84% | 4.3 (0.8 to 7.7) | 0.015 |
| 80 years or more x male | 100% | 8.1 (4.0 to 12.3) | <0.001 |
| IMD 2004 score (10 units) | 97% | −0.6 (−1.0 to −0.2) | 0.008 |
| BMI, kg/m2 (10 units) | 96% | −1.5 (−2.4 to −0.6) | 0.001 |
| EQ-5D-3L 5th question (No) | |||
| Anxiety/depression | 98% | −1.6 (−2.5 to −0.6) | 0.001 |
| OKS baseline | 100% | 0.4 (0.3 to 0.4) | <0.001 |
| ASA grade (Fit and healthy) | |||
| Asymptomatic no restriction | 55% | ─ | ─ |
| Symptomatic minimal/severe restriction | 97% | −2.0 (−3.2 to −0.8) | 0.001 |
| Previous knee arthroscopy (No) | |||
| Yes | 82% | −1.6 (−3.0 to −0.2) | 0.025 |
| Other condition affecting mobility (No) | |||
| Yes | 100% | −3.3 (−4.7 to −2.0) | <0.001 |
| Fixed flexion deformity (No) | |||
| Yes | 100% | 1.7 (0.8 to 2.6) | <0.001 |
| Pre-operative ACL (Intact) | |||
| Damaged/absent | 81% | 1.0 (0.1 to 2.0) | 0.029 |
| R 2 | 19.3% | ||
| Optimism | 1.6 | ||
| Bias-corrected R 2 | 17.6% | ||