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Table 3 Multiple linear regression analyses of demographic, clinical, symptom, and psychological factors on pre- and postoperative self-rated health in patients undergoing total knee arthroplasty (TKA)

From: The relationship between pain with walking and self-rated health 12 months following total knee arthroplasty: a longitudinal study

Independent variables Beta B 95% CI Explained variance (R 2) Change of variance (R 2 –change) P-value
Self-rated health prior to surgery
Step 1. Demographic characteristics     8.5% 8.5% .001
  Age .06 .12 −.18 to .42    
  Sex (male as reference) −.08 −3.39 −9.16 to 2.39   
Step 2. Clinical characteristics     18.2% 9.7% <.001
  Number of comorbidities −.05 −1.02 −3.69 to 1.66    
  C-reactive protein −.25 −1.63 −2.51 to−.74   
Step 3. Pain characteristics     25% 6.8% <.001
  Number of painful sites before surgery −.18 −2.17 −3.88 to−.46    
Step 4 Preoperative symptoms     32.7% 7.7% <.001
  Fatigue severity (higher = more fatigue) −.22 −1.99 −3.45 to−.54    
Step5 Psychological characteristics     37.0% 4.3% .002
  Illness concern (higher = more concern) −.24 −1.82 −2.97 to−.66    
Self-rated health 12 months after TKA
Step 1. Demographic characteristics     3.5% 3.5% .12
  Age −.02 −.04 −.27 to .20    
  Sex (male as reference) .06 1.99 −2.53 to 6.52   
Step 2. Clinical characteristics     15.8% 12.3% <.001
  Body mass index −.15 −.53 −.98 to−.07    
  Number of comorbidities .07 −1.11 −3.19 to .96   
Step 3. Pain characteristics     42.9% 27.1% <.001
  Number of painful sites 12 months after surgery −.17 −2.18 −3.93 to−.42    
  Pain interference walking group (Continuous improvement group as reference) −.33 −12.45 -.17.67 to -7.24   
Step 4 Perioperative characteristics     45.3% 2.4% .025
  Ketamine Yes/No – No as reference −0.15 −6.95 −12.80 to −1.10    
Step 5 Preoperative symptoms     51.0% 5.7% <.001
  Depression −.21 −1.08 −1.80 to .37    
Step 6 Psychological characteristics     52.9% 1.8% .04
  Personal control .12 .84 −1.74 to .07    
Step 7 Health characteristics     56.1% 3.2% .005
  Preoperative self-rated health .21 .17 .05 to .29    
  1. Statistically significant defined as p ≤ 0.05. Bold coefficient = statistically significant
  2. Abbreviations: Beta standardized beta coefficient, B unstandardized coefficient, CI confidence interval, SE standard error