Table 3 Results of the sequential multiple regression analysis (N = 85a): Variance explained in the global effectiveness of total hip arthroplasty at 12 months follow-up by sociodemographic and medical variables, preoperative expectations, change in symptoms and the fulfilment of expectations (multiple imputation of missing values)
|  | Variables included upon each step | Range of R2 across the 10 imputed data sets | Pooled β (p-value) in final model (only significant predictor variables shown) |
|---|---|---|---|
Step 1 Confounding factors | Degree of school education Average hip pain in the last 3 months before surgery Overall severity of chronic pain (CPG) Hip function and mobility (WOMAC) Walking ability (Timed up and go score) | 0.261–0.304 | – |
Step 2 Preoperative expectations | Degree of school education Average hip pain in the last 3 months before surgery Overall severity of chronic pain (CPG) Hip function and mobility (WOMAC) Walking ability (Timed up and go score) Preoperative hip pain expectation | 0.372–0.416 | β = −2.143 (p = 0.033) Walking ability (Timed up and go score) β = 3.745 (p < 0.001) Preoperative hip pain expectation |
Step 3 Improvement in symptoms (Symptom change scores) | Degree of school education Average hip pain in the last 3 months before surgery Overall severity of chronic pain (CPG) Hip function and mobility (WOMAC) Walking ability (Timed up and go score) Preoperative hip pain expectation Symptom change scores: Average hip pain in the last 3 months hip function and mobility (WOMAC) Health-related quality of life (SF-12 physical) | 0.419–0.493 | β = − 2.338 (p = 0.020) Walking ability (Timed up and go score) β = 3.370 (p = 0.001) Preoperative hip pain expectation |
Step 4 Fulfillment of expectations (calculated expectations-actuality discrepancy scores) | Degree of school education Average hip pain in the last 3 months before surgery Overall severity of chronic pain (CPG) Hip function and mobility (WOMAC) Walking ability (Timed up and go score) Preoperative hip pain expectation Symptom change scores: Average hip pain in the last 3 months Hip function and mobility (WOMAC) Health-related quality of life (SF-12 physical) Calculated expectations-actuality discrepancy scores: Walking ability Independence Physical exercise General function Social interactions | 0.613–0.689 | β = −3.103 (p = 0.002) Walking ability (Timed up and go score) β = 4.605 (p < 0.0001) Preoperative hip pain expectation β = 2.601 (p = 0.009) Fulfillment of expectations (calculated expectations-actuality discrepancy scores): Walking ability β = 2.952 (p = 0.002) Fulfillment of expectations (calculated expectations-actuality discrepancy scores):: Independence β = − 2.783 (p = 0.006) Fulfillment of expectations (calculated expectations-actuality discrepancy scores): General function |
Final model (only significant predictors included) | Walking ability (Timed up and go score) Preoperative hip pain expectation Calculated expectations-actuality discrepancy scores: Walking ability Independence General function | 0.510–0.544 |  |