Table 4. Multiple regression models for post-surgical KOA pain intensity, and for percentage residual pain at 6-months post-surgery, for four different pain intensity measures.
| Post-surgical Pain Intensity | ||||||
|---|---|---|---|---|---|---|
| Model | b | SE | β | t | p | Adjusted R2 |
| BPI Pain Severity | ||||||
| Affect | 2.845 | .670 | .408 | 4.246 | .000 | .238** F(2,82) = 13.952 |
| Pain Duration | .277 | .096 | .278 | 2.893 | .005 | |
| NRS | ||||||
| No predictive model–no variables entered in the equation. | ||||||
| KOOS Pain | ||||||
| Affect | 5.688 | 2.229 | .284 | 2.522 | .013 | |
| Gender | 9.756 | 4.320 | .221 | 2.259 | .027 | |
| Health | 4.246 | 2.026 | .231 | 2.060 | .043 | |
| .234** F(3,81) = 9.338 |
||||||
| SF36 Pain | ||||||
| Health | 7.032 | 2.292 | .310 | 3.068 | .003 | |
| Gender | 15.176 | 5.520 | .278 | 2.749 | .007 | |
| .196* F(2,82) = 9.730 |
||||||
| % Residual Pain | ||||||
| Model | b | SE | β | t | p | Adjusted R2 |
| BPI Pain Severity | ||||||
| Pain Duration | 1.413 | .536 | .274 | 2.635 | .01 | |
| Health | 7.681 | 3.451 | .232 | 2.226 | 0.029 | |
| .114** F(2,82) = 6.267 |
||||||
| NRS | ||||||
| No predictive model–no variables entered in the equation. | ||||||
| KOOS Pain | ||||||
| Physical Performance | 9.276 | 3.036 | .321 | 3.055 | .003 | |
| .092** F(1,83) = 9.335 |
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| SF36 Pain | ||||||
| Gender | 24.210 | 8.088 | .316 | 2.993 | .004 | |
| .088** F(1,83) = 8.959 |
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Different explanatory models were elicited for absolute versus relative (% residual pain) pain intensity after surgery, with the variance explained by each model being overall lower for % residual pain than that for absolute pain intensity. Again, explanatory variables were also distinct considering the four different outcome measures.
b, unstandardized regression coefficient; SE, standard error; β, standardized regression coefficient; F, obtain F-value; t, obtained t-value; R2, proportion variance explained. Gender: male coded as 0, female coded as 1.
* p ≤ 0.05
**p ≤ 0.01. Displayed statistics are from the final step for each dependent variable.
BPI Severity, Brief Pain Inventory Pain: severity subscale; HOOS Pain, Hip Injury and Osteoarthritis Outcome Score: pain subscale; NRS, Numeric Rating Scale; SF36 Pain, Short-form (36) Health Survey: pain subscale.