Multivariable mixed-effects gamma regression: relation between covariates and time from hemiarthroplasty to reoperation*
| Covariate | First reoperation (n = 154) | All reoperations (n = 229) | ||
|---|---|---|---|---|
| Risk ratio ± SE (95% CI) | p value | Risk ratio ± SE (95% CI) | p value | |
| Age at hemiarthroplasty | 0.98 ± 0.01 (0.95–1.00) | 0.046 | 0.97 ± 0.01 (0.95–0.99) | 0.001 |
| Dislocation | 0.32 ± 0.09 (0.18–0.56) | < 0.001 | 0.5 ± 0.1 (0.30–0.81) | 0.006 |
| Dementia | 0.5 ± 0.1 (0.3–0.9) | 0.012 | 0.4 ± 0.1 (0.27–0.72) | 0.001 |
| Acetabular wear | 4 ± 1 (1.8–7.5) | < 0.001 | 2.4 ± 0.8 (1.3–4.5) | 0.005 |
| Infection | 0.6 ± 0.2 (0.33–1.3) | 0.2 | 0.6 ± 0.1 (0.37–0.96) | 0.033 |
CI = confidence interval; SE = standard error.
↵* n = 229 reoperations including 154 first reoperations in 154 hips; 1 additional hip had 1 reoperation that was excluded because of missing risk factor data.