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)

  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

  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