Table 1.
Multivariate Cox model for conversion to THA
| Variable | Unit | Rate ratio | Lower confidence interval | Upper confidence interval | p Value | Log rate ratio | SE |
|---|---|---|---|---|---|---|---|
| Age | Per year | 1.06 | 1.03 | 1.08 | 0 | 0.055 | 0.012 |
| Preoperative modified Harris hip score | Per unit | 0.98 | 0.96 | 0.99 | < 0.001 | −0.025 | 0.007 |
| Femoral anteversion | Per unit | 0.97 | 0.94 | 0.99 | 0.0111 | −0.034 | 0.014 |
| Lateral center-edge angle | Per degree | 0.93 | 0.89 | 0.97 | < 0.001 | −0.074 | 0.02 |
| Revision surgery | Yes vs no | 2.4 | 1.15 | 5.01 | 0.0193 | 0.877 | 0.375 |
| Acetabular cartilage damage grade | 1 vs 0 | 0.29 | 0.06 | 1.35 | 0.115 | −1.22 | 0.77 |
| Acetabular cartilage damage grade | 2 vs 0 | 0.87 | 0.24 | 3.11 | 0.831 | −0.14 | 0.65 |
| Acetabular cartilage damage grade | 3 vs 0 | 1.8 | 0.5 | 6.47 | 0.368 | 0.59 | 0.65 |
| Acetabular cartilage damage grade | 4 vs 0 | 1.95 | 0.54 | 7.04 | 0.311 | 0.67 | 0.66 |
| Femoral cartilage damage grade | 1 vs 0 | 0.59 | 0.08 | 4.42 | 0.606 | −0.53 | 1.03 |
| Femoral cartilage damage grade | 2 vs 0 | 2.23 | 1.11 | 4.46 | 0.023 | 0.8 | 0.35 |
| Femoral cartilage damage grade | 3 vs 0 | 2.17 | 1.11 | 4.23 | 0.024 | 0.77 | 0.34 |
| Femoral cartilage damage grade | 4 vs 0 | 2.96 | 1.34 | 6.52 | 0.007 | 1.09 | 0.4 |
| Acetabuloplasty | Yes vs no | 1.83 | 1.03 | 3.24 | 0.038 | 0.604 | 0.291 |
| Femoral osteoplasty | Yes vs no | 0.62 | 0.36 | 1.06 | 0.0809 | −0.484 | 0.277 |
| Harrell C statistic | 0.832 |
SE = standard error.