Table 4.
Performance of claims-based risk-prediction models
| Performance statistic | THA | TKA | ||
|---|---|---|---|---|
| Claims model | Claims + clinical model | Claims model | Claims + clinical model | |
| Model accuracy index (original/bias-corrected) | ||||
| C statistic | 0.662/0.629 | 0.706/0.665 | 0.621/0.585 | 0.648/0.606 |
| Somers’ Dxy statistic | 0.325/0.258 | 0.411/0.330 | 0.241/0.169 | 0.295/0.212 |
| R2 (%) | 0.028/0.013 | 0.042/0.021 | 0.017/0.007 | 0.023/0.009 |
| Comparison of models (improvement, 95% CI or p value) | ||||
| Difference in C statistic | 0.043 (0.012–0.074)* | 0.027 (0.007–0.047)* | ||
| Difference in log-likelihood | 37.4 (p < 0.001) | 17.0 (p = 0.009) | ||
| Integrated discrimination improvement in subjects with surgical site infection | 0.36% (0.11%–0.61%) | 0.09% (−0.02% to 0.20%) | ||
| Integrated discrimination improvement subjects without surgical site infection | 0.01% (−0.01% to 0.03%) | 0.00% (−0.01% to 0.02%) | ||
| Aggregate integrated discrimination improvement (equal-weighting of two groups) | 0.37% (0.12%–0.62%) | 0.09% (−0.02% to 0.21%) | ||
* CIs calculated using the jackknife.