Table 7.
Hazard ratios (HR), 95% confidence intervals, and significance levels for the Cox regression model, adjusted for known confounders. Only cases with no missing values included in the model
| Variable (reference variable) | n | HR (95% CI) | p-value |
|---|---|---|---|
| Age at primary | 0.98 (0.97–0.98) | < 0.001 | |
| Sex | |||
| Male | 101,343 | Reference | |
| Female | 191,623 | 0.78 (0.73–0.83) | < 0.001 |
| Stem type | < 0.001 | ||
| Exeter | 176,350 | Reference | |
| All other taper-slip | 69,036 | 1.21 (1.12–1.30) | < 0.001 |
| Charnley | 23,140 | 1.15 (1.03–1.28) | 0.01 |
| All other composite beam | 24,440 | 1.19 (1.06–1.33) | 0.003 |
| Diagnosis | < 0.001 | ||
| Osteoarthritis | 264,745 | Reference | |
| Other arthritides | 4,315 | 1.23 (0.98–1.54) | 0.07 |
| Previous trauma | 3,718 | 1.47 (1.13–1.90) | 0.004 |
| Acute trauma | 6,890 | 1.84 (1.52–2.22) | < 0.001 |
| Previous hip surgery | 536 | 1.44 (0.75–2.78) | 0.3 |
| DDH/childhood disease | 2,846 | 0.77 (0.56–1.07) | 0.1 |
| Avascular head necrosis | 7,305 | 1.44 (1.22–1.70) | < 0.001 |
| Other (including infection) | 2,611 | 1.38 (1.03–1.85) | 0.03 |
| ASA grade | < 0.001 | ||
| 1 | 40,449 | Reference | |
| 2 | 200,973 | 1.20 (1.09–1.32) | < 0.001 |
| 3 | 49,580 | 1.32 (1.18–1.49) | < 0.001 |
| 4 | 1,887 | 1.17 (0.76–1.82) | 0.5 |
| 5 | 77 | 0.001 (0–2.3x1021) | 0.8 |
| Procedure type | |||
| Routine | 275,341 | Reference | |
| Complex | 17,625 | 0.99 (0.76–1.25) | 0.9 |
| Approach | 0.1 | ||
| Posterior | 137,176 | Reference | |
| Trans gluteal | 129,450 | 0.93 (0.87–1.00) | 0.049 |
| Trochanteric osteotomy | 2,067 | 1.14 (0.79–1.64) | 0.5 |
| Other | 10,020 | 0.83 (0.67–1.03) | 0.09 |
| Missing/unknown | 14,253 | 0.83 (0.64–1.08) | 0.2 |
| Bearing | < 0.001 | ||
| Metal-on-polyethylene | 257,685 | Reference | |
| Ceramic-on-ceramic | 16,330 | 0.68 (0.58–0.79) | < 0.001 |
| Ceramic-on-polyethylene | 18,562 | 0.61 (0.52–0.71) | < 0.001 |
| Ceramic-on-metal | 389 | 1.39 (0.74–2.58) | 0.3 |