Table 1.
Multivariable Analysis of Overall OKS at 1 Year, and over 5 and 10 Years After TKA.
| Variables | At 1 y (n = 1636) |
Over 5 y (n = 1967) |
Over 10 y (n = 1980) |
|---|---|---|---|
| Multivariablea Coefficient (95% CI) |
Multivariablea Coefficient (95% CI) |
Multivariablea Coefficient (95% CI) |
|
| R2 = 18.76% | R2 = 15.62% | R2 = 14.51% | |
| Patient characteristics | |||
| Sex | |||
| Female | 0 | 0 | 0 |
| Male | 0.44 (−1.05, 1.92) | 0.33 (−0.96, 1.61) | 0.31 (−0.96, 1.58) |
| Age at operation (y) | |||
| <60 | −0.86 (−3.18, 1.46) | −2.09 (−3.89, −0.30)∗ | −1.96 (−3.73, −0.20)∗ |
| 60-70 | 0 | 0 | 0 |
| 70-80 | 0.74 (−0.59, 2.08) | 0.07 (−1.11, 1.25) | −0.28 (−1.45, 0.88) |
| 80+ | −2.75 (−4.98, −0.51)∗ | −2.92 (−4.73, −1.10)∗∗ | −3.23 (−5.03, −1.42)∗∗∗ |
| Sex#age at operationb | |||
| Male#age < 60 | −4.29 (−7.80, −0.78)∗ | −1.90 (−4.63, 0.83) | −1.94 (−4.64, 0.76) |
| Male#age 60-70 | −0.53 (−2.48, 1.41) | −0.10 (−1.83, 1.62) | −0.15 (−1.86, 1.55) |
| Male#age 80+ | 2.74 (−0.36, 5.84)† | 3.57 (0.90, 6.23)∗∗ | 3.42 (0.76, 6.08)∗ |
| Marital status | |||
| Married | 0 | 0 | 0 |
| Living alone | −0.48 (−1.48, 0.52) | −0.65 (−1.52, 0.21)† | −0.72 (−1.59, 0.15)† |
| BMI (kg/m2) | |||
| <25 | 0 | 0 | 0 |
| 25-30 | −0.33 (−1.55, 0.90) | −0.36 (−1.45, 0.73) | −0.36 (−1.40, 0.69) |
| 30-35 | −1.84 (−3.23, −0.46)∗∗ | −0.95 (−2.11, 0.21)† | −0.92 (−2.06, 0.21)† |
| >35 | −1.97 (−3.62, −0.32)∗ | −1.67 (−3.07, −0.27)∗ | −1.79 (−3.12, −0.46)∗∗ |
| IMD 2004 quintiles | |||
| 1st (most deprived) | 0 | 0 | 0 |
| 2nd | 1.22 (−0.82, 3.25) | 0.39 (−0.53, 1.32) | 0.39 (−0.28, 1.05) |
| 3rd | 2.38 (0.47, 4.29)∗ | 1.08 (0.19, 1.98)∗ | 0.82 (0.21, 1.43)∗∗ |
| 4th | 2.70 (0.86, 4.53)∗∗ | 1.07 (0.17, 1.97)∗ | 0.96 (0.35, 1.58)∗∗ |
| 5th (most affluent) | 1.97 (0.04, 3.91)∗ | 1.08 (0.15, 2.02)∗ | 0.94 (0.26, 1.61)∗∗ |
| Preoperative patient-reported health status | |||
| Preop overall OKS | 0.35 (0.29, 0.42)∗∗∗ | 0.39 (0.34, 0.45)∗∗∗ | 0.41 (0.35, 0.46)∗∗∗ |
| Preop SF-12 MCS | |||
| <50 | 0 | 0 | 0 |
| 50+ | 1.65 (−0.70, 2.61)∗∗ | 1.77 (0.96, 2.57)∗∗∗ | 1.61 (0.81, 2.40)∗∗∗ |
| Preoperative clinical conditions | |||
| ASA grade | |||
| Fit and healthy | 0 | 0 | 0 |
| Asymptomatic | −1.04 (−2.25, 0.17)† | −0.81 (−1.83, 0.21)† | −0.66 (−1.60, 0.28) |
| Symptomatic | −2.69 (−4.25, −1.13)∗∗ | −2.19 (−3.43, −0.95)∗∗ | −1.91 (−3.07, −0.75)∗∗ |
| Previous knee surgery | |||
| No | 0 | 0 | 0 |
| Yes | −1.78 (−2.72, −0.84)∗∗∗ | −1.24 (−2.07, −0.42)∗∗ | −1.17 (−1.98, −0.36)∗∗ |
| Comorbidities | |||
| No | 0 | 0 | 0 |
| Yes | −3.00 (−4.35, −1.65)∗∗∗ | −2.37 (−3.50, −1.24)∗∗∗ | −2.24 (−3.36, −1.12)∗∗∗ |
| Year of follow-up | −0.16 (−0.25, −0.06)∗∗ | −0.33 (−0.38, −0.27)∗∗∗ | |
Coefficient: the regression coefficient represents the difference in outcome compared with the reference group. A positive value indicates that the group has better postoperative pain/function.
OKS, Oxford knee score; TKA, total knee arthroplasty; CI, confidence interval; IMD, Index of Multiple Deprivation; BMI, body mass index; SF-12 MCS, 12-item Short-Form Health Survey Mental Component Summary; ASA, American Society of Anesthesiologists.
∗∗∗<.001; ∗∗<.01; ∗<.05; †<.20.
a
In the multivariable models, all variables are mutually adjusted and an interaction term between age and sex was included.
b
Interaction between sex and age at operation.