Table 5.
Characteristics assessed for unweighted and weighted standardized mean difference (SMD) following propensity score weighting, using the average treatment effect for the treated (ATT) estimation
| Variable | Unweighted cohort | Propensity score weighting cohort | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| TXA | non-TXA | SMD (%) | TXA | non-TXA | SMD (%) | ||||||
| (n = 3664) | (n = 4377) | (n = 3664) | (n = 3637) | ||||||||
| Age, year (mean ± SD) | 67.6 | ± 10.6 | 68.1 | ± 10.0 | 4.2 | 67.6 | ± 10.6 | 67.9 | ± 10.3 | 2.4 | |
| Male (n, %) | 1047 | (28.6) | 1189 | (27.2) | 3.2 | 1047 | (28.6) | 1067 | (29.3) | 1.7 | |
| Surgery: TKA (n, %) | 2695 | (73.6) | 3581 | (81.8) | 19.9 | 2695 | (73.6) | 2707 | (74.4) | 2.0 | |
| BMI, kg/m2 (mean ± SD) | 26.9 | ± 4.5 | 26.9 | ± 4.1 | 0.3 | 26.9 | ± 4.5 | 26.9 | ± 4.3 | 0.4 | |
| Laterality (n, %) | 1.4 | 0.9 | |||||||||
| Left | 1913 | (52.2) | 2285 | (52.2) | 1913 | (52.2) | 1896 | (52.1) | |||
| Right | 1749 | (47.7) | 2088 | (47.7) | 1749 | (47.7) | 1740 | (47.8) | |||
| Bilateral | 2 | (0.1) | 4 | (0.1) | 2 | (0.1) | 1 | (0.1) | |||
| Preoperative Hb, g/dL (mean ± SD) | 12.2 | ± 1.8 | 12.8 | ± 1.7 | 34.3 | 12.2 | ± 1.8 | 12.1 | ± 1.8 | 1.4 | |
| Surgical time, min (mean ± SD) | 142 | ± 31 | 154 | ± 31 | 40.0 | 142 | ± 31 | 143 | ± 25 | 4.6 | |
| CCI > 2 (n, %) | 2258 | (61.7) | 3964 | (67.7) | 12.7 | 2258 | (61.6) | 2263 | (62.2) | 1.3 | |
| ASA > 3 (n, %) | 1476 | (40.3) | 3687 | (16.9) | 7.3 | 1477 | (40.3) | 1469 | (40.4) | 0.2 | |
| General anesthesia (n, %) | 3227 | (88.1) | 4026 | (92.0) | 13.0 | 437 | (11.9) | 451 | (12.4) | 1.4 | |
SMD, standardized mean difference; TXA, tranexamic acid; TKA, total knee arthroplasty; CCI, Charlson Comorbidity Index; ASA, American Society of Anesthesiology score