TABLE I.
Results of the Fixed-Registry-Effects Analysis Comparing C-C and M-HXLPE Implants
| Hazard Ratio (95% CI)* |
||
| >28-mm C-C, Relative to All M-HXLPE† | ≤28-mm C-C, Relative to All M-HXLPE‡ | |
| Time in yr | ||
| 0 to 1 | Ref. | Ref. |
| 1 to 2 | 6.72 (5.07-8.92) | 5.74 (4.20-7.80) |
| 2 to 3 | 8.24 (6.16-11.01) | 7.00 (5.11-9.59) |
| 3 to 4 | 9.88 (7.37-13.24) | 7.98 (5.82-10.95) |
| 4 to 5 | 10.84 (8.08-14.55) | 8.80 (6.40-12.08) |
| 5 to 6 | 12.11 (9.00-16.30) | 9.73 (7.07-13.40) |
| 6 to 7 | 13.04 (9.64-17.63) | 10.41 (7.54-14.36) |
| 7 to 8 | 15.19 (11.12-20.75) | 12.08 (8.67-16.83) |
| 8 to 9 | 15.84 (11.29-22.21) | 12.52 (8.65-18.11) |
| 9 to 10 | NA | 14.09 (9.10-21.81) |
| Sex | ||
| Male | Ref. | Ref. |
| Female | 1.09 (0.93-1.28) | 0.98 (0.81-1.19) |
| Age in yr | ||
| 45 to 54 | Ref. | Ref. |
| 55 to 64 | 0.80 (0.66-0.96) | 0.89 (0.71-1.12) |
| Fixed registry effects§ | — | — |
| Bearing surface and size | ||
| Overall | NA | 1.36 (1.09-1.68) |
| 0 to 2 yr# | 0.77 (0.63-0.93) | NA |
| 2 to 6 yr# | 0.88 (0.74-1.05) | NA |
| 6 to 9 yr# | 0.93 (0.77-1.12) | NA |
*
Results are based on an iterative solution that updates the residual covariances until convergence. Confidence intervals are based on a Z distribution. NA = not applicable.
†
The estimated intercept was −5.69 (SE, 0.17).
‡
The estimated intercept was −5.51 (SE, 0.19).
§
Fixed registry effects were included in this model, but the results are omitted from this table because a precondition of data sharing was no reporting of comparisons among registries.
#
The bearing effects over time are based on a combination of the main and interaction effects from the model.