Table 2.
Baseline characteristics of patients undergoing primary TKA for continuous variables
| Geneva registry Switzerland (N = 823) | FORCE-TJR United States (N = 6,680) | Mean difference (95% CI) | P-value**** | |
|---|---|---|---|---|
| Age at operation, mean [±SD] | 72.3 [±9.4] | 66.7 [±9.4] | 5.6 (4.9; 6.3) | 0.000 |
| Preoperative BMI, mean [±SD]* | 29.6 [±5.9] | 31.53 [±6.2] | -1.9 (-1.5; -2.4) | 0.000 |
| Mean age in each BMI category, [±SD] | ||||
| <25 | 72.9 [±10.9] | 69.38 [±10.2] | 3.5 (1.8; 5.2) | 0.000 |
| 25–29.9 | 74.25 [±8.6] | 68.51 [±9.4] | 5.8 (4.6; 6.9) | 0.000 |
| 30–34.9 | 71.02 [±8.8] | 66.64 [±8.7] | 4.4 (3.1; 5.6) | 0.000 |
| ≥35 | 69.16 [±8.7] | 63.29 [±8.5] | 5.9 (4.4; 7.3) | 0.000 |
| Preoperative scores, mean [±SD] | Mean difference | |||
| (95% CI)/Effect size | ||||
| WOMAC pain | 41.0 [±17.9] | 51.59 [±19.0] | -10.6 (-12.2; -9.1)/0.57 | 0.000 |
| WOMAC function | 44.82 [±19.2] | 52.09 [±18.6] | -7.3 (-8.9; -5.7)/0.39 | 0.000 |
| SF-12 Physical Component Summary | 34.45 [±7.6] | 32.68 [±8.3] | 1.8 (1.1; -2.5)/0.23 | 0.000 |
| SF-12 Mental Component Summary | 44.84 [±11.2] | 51.40 [±12.3] | -6.6 (-7.6; -5.5)/0.56 | 0.000 |
*BMI was available for 6,452 TKAs (96.6%) from FORCE-TJR
**In the Geneva cohort information on education was routinely collected only since 2012
***FORCE-TJR collects RA versus OA
****Pearson chi2 tests were used for categorical variables, and two-sample Wilcoxon rank-sum (Mann-Whitney) tests were used for continuous variables