Preoperative predictors of a good TKA outcome*: results of multivariable robust Poisson regression
| Preoperative predictors | Dependent variable: good TKA outcome* (yes vs no) | ||
| Unadjusted risk ratio (RR) (95% CI) | Adjusted RR † (95% CI) | P value | |
| TKA need | |||
| WOMAC Pain Score, per 10-unit increase KOOS-PS, per 10-unit increase | 1.06 (1.04 to 1.08) 1.07 (1.05 to 1.09) | 1.03 (1.01 to 1.05) 1.06 (1.03 to 1.08) | 0.01 <0.0001 |
| Health status | |||
| Troublesome contralateral knee Low back pain | 1.09 (1.02 to 1.16) 0.97 (0.90 to 1.05) | 1.05 (0.99 to 1.12) 0.93 (0.87 to 1.00) | 0.13 0.06 |
| Readiness/willingness | |||
| PHQ-8 depression, per 10-unit increase PASS knee symptoms, unacceptable ‘Definitely willing’ to undergo TKA | 1.05 (1.00 to 1.11) 1.26 (1.13 to 1.39) 1.26 (1.10 to 1.44) | 0.94 (0.89 to 0.99) 1.14 (1.03 to 1.27) 1.20 (1.05 to 1.37) | 0.04 0.02 0.007 |
| TKA expectations | |||
| Go upstairs Perform daily activities Kneel Perform recreational activities Improve psychological well-being | 1.19 (1.05 to 1.33) 1.03 (0.94 to 1.12) 1.00 (0.94 to 1.17) 1.08 (0.99 to 1.17) 0.99 (0.22 to 1.06) | 1.15 (1.02 to 1.30) 0.92 (0.84 to 1.02) 0.93 (0.87 to 0.99) 1.10 (1.01 to 1.20) 0.92 (0.86 to 0.99) | 0.02 0.10 0.03 0.04 0.04 |
| Patient age, per 10-year increase | 1.00 (0.99 to 1.00) | 1.03 (1.00 to 1.07) | 0.10 |
*Met Outcome Measures in Rheumatology and Osteoarthritis Research Society International (OMERACT–OARSI) response criteria+reported being somewhat or very satisfied overall with TKA results.
†RRs adjusted for all other variables in the model.
KOOS-PS, Knee injury and Osteoarthritis Outcome Score physical function short-form; PASS, Patient Acceptable Symptom State; PHQ-8, Patient Health Questionnaire; TKA, total knee arthroplasty; WOMAC, Western Ontario-McMaster Universities Osteoarthritis Index.