Table 2.
Observed number of deaths (Obs) (all causes) and standardised mortality ratio (SMR) and rate ratio (RR) among patients with metal-on-metal and metal-on-polyethylene total hip prostheses for osteoarthritis by number of postoperative years.
| Follow-up time, completed years | Metal-on-metal prosthesis (n = 579) | Metal-on-polyethylene prosthesis (n = 1585) | ||||||
|---|---|---|---|---|---|---|---|---|
| Obs | SMR | 95% CI‡ | Obs | SMR | 95% CI | RR | 95% CI | |
| 0 to 1 | 16 | 0.59 | 0.34-0.96* | 35 | 0.37 | 0.26-0.51*** | 1.61 | 0.83-2.98 |
| 2 through 9 | 122 | 0.77 | 0.64-0.91** | 342 | 0.70 | 0.63-0.78*** | 1.09 | 0.88-1.35 |
| 10 through 19 | 200 | 0.94 | 0.81-1.06 | 611 | 0.96 | 0.89-1.04 | 0.97 | 0.82-1.14 |
| 20+ | 190 | 1.20 | 1.04-1.37 * | 311 | 1.38 | 1.23-1.53*** | 0.87 | 0.72-1.05 |
| Total | 528 | 0.95 | 0.87-1.02 | 1299 | 0.90 | 0.85-0.95*** | 1.05 | 0.95-1.16 |
‡ 95% CI, 95% confidence interval
*p < 0.05, **p < 0.01, *** p < 0.001