Table 2. Multivariable-Adjusted Logistic Regression Model Assessing Pre–Total Knee Arthroplasty (TKA) Factors Associated With the Slow Pain Responder Trajectorya.
| Variable | Full Modelb | |
|---|---|---|
| OR (95% CI) | P Value | |
| Preoperative SF-36 MCS score, with 1-unit increase | 0.98 (0.96-1.00) | .02 |
| Preoperative KOOS activities of daily living score for surgical knee, with 1-unit increase | 0.97 (0.95-0.99) | .007 |
| Sex | ||
| Male | 1 [Reference] | NA |
| Female | 1.13 (0.73-1.73) | .58 |
| Age, y | ||
| <65 | 1 [Reference] | NA |
| ≥65 | 0.97 (0.63-1.49) | .21 |
| BMI | ||
| <25 | ||
| 25-29.9 | 1.97 (1.00-3.84) | .05 |
| 30-34.9 | 1.12 (0.56-2.24) | .74 |
| ≥35 | 1.43 (0.69-2.95) | .34 |
| Race | ||
| White | 1 [Reference] | NA |
| Nonwhite | 1.56 (0.70-3.49) | NA |
| Charlson Comorbidity Index Score | ||
| 0 | 1 [Reference] | NA |
| 1 | 1.25 (0.79-2.00) | .34 |
| 2 | 1.20 (0.60-2.40) | .42 |
| ≥3 | 0.78 (0.32-1.91) | .35 |
| Previous joint replacement surgery | 0.82 (0.52-1.27) | .37 |
| No | 1 [Reference] | NA |
| Oswestry Disability Index low back pain | ||
| None | 1 [Reference] | NA |
| Mild | 0.93 (0.58-1.49) | .76 |
| Moderate | 0.92 (0.53-1.58) | .76 |
| Severe | 0.87 (0.40-1.90) | .72 |
| Nonsurgical joints with moderate to severe pain, No. | ||
| 0 | 1 [Reference] | NA |
| 1 | 0.91 (0.54-1.51) | .70 |
| 2 | 1.17 (0.43-3.15) | .76 |
| 3 | 0.73 (0.17-3.07) | .67 |
| Preoperative SF-36 PCS score, with 1-unit increase | 1.00 (0.97-1.03) | .95 |
| Preoperative KOOS pain score for surgical knee, with 1-unit increase | 1.02 (1.00-1.04) | .06 |
| Area under the receiver operating characteristic curve | 0.64 | NA |
Abbreviations: BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); KOOS, Knee Injury and Osteoarthritis Outcome Score; MCS, mental component summary; NA, not applicable; OR, odds ratio; PCS, physical component summary; SF-36, 36-Item Short Form Health Survey.
No evidence of multicollinearity was found because the variance inflation factors for each of the variables were 1.08 or lower (as a rule of thumb, a variable whose variance inflation factor values are greater than 10 may merit further investigation). Multivariable-adjusted logistic regression included the following factors: sex, age, BMI, race, preoperative Charlson Comorbidity Index score, previous joint replacement surgery, preoperative Oswestry Disability Index low back pain, preoperative number of nonsurgical joints with moderate to severe pain, preoperative SF-36 PCS score and MCS score, preoperative KOOS pain score for surgical knee, and KOOS activities of daily living score.
Only significant variables are listed in the table (significance level, P ≤ .05).