Table 1 Potential predictors to self-rated health prior to surgery and 12 months following total knee arthroplasty – Pearsons bivariate correlation coefficient

 Age

0.21⁺

**

0.19⁺

*

 Sex (male as reference)

−0.20⁺

*

0.02⁺

 Cohabitation status (living with partner as reference)

0.08

−0.03

 Employment status (paid work as reference)

0.11

0.01

 Education level (less than 14 years as reference)

0.01

0.04

 Body mass index

−0.18⁺

*

−0.30⁺

**

 Number of comorbidities (0–5)

−0.20⁺

*

−0.26⁺

**

 American Society of Anesthesiologists’ physical status classification (1–3)

0.01

−0.05

 Systolic blood pressure

0.17⁺

*

0.09

 C-reactive protein

−0.30⁺

**

−0.15

 Creatinine

0.17⁺

*

0.08

 Average pain prior to surgery

−0.31⁺

**

−0.16⁺

*

 Worst pain prior to surgery

−0.35⁺

**

−0.31⁺

**

 Pain interference with function prior to surgery

−0.43⁺

**

−0.36⁺

**

 Number of painful sites prior to surgery

−0.33⁺

**

−0.27⁺

**

 Number of painful sites 12 months

n/a

−0.35⁺

**

 Contralateral knee pain 12 months

n/a

−0.06

 Pain interference with walking group (Continuous improvement group as reference)

n/a

−0.55⁺

**

 Type of anesthesia (regional anesthesia as reference)

0.01

−0.17⁺

*

 Length of surgery (minutes)

n/a

−0.06

 Length of stay (days)

n/a

−0.06

 Ketamine (no as reference)

n/a

−0.24⁺

**

 Average dose of opioids over 4 days

n/a

−0.10

 Fatigue severity (Lee fatigue scale total score)

−0.44⁺

**

−0.33⁺

**

 Fatigue interference (Fatigue Severity Scale)

−0.38⁺

**

−0.36⁺

**

 Depression

−0.32⁺

**

−0.43⁺

**

 Anxiety

−0.32⁺

**

−0.31⁺

**

 Consequences

−0.35⁺

**

−0.21⁺

**

 Personal control

−0.20⁺

*

−0.31⁺

**

 Identity

−0.29⁺

**

−0.21⁺

**

 Illness concern

−0.43⁺

**

−0.31⁺

**

 Emotional response

−0.37⁺

**

−0.23⁺

**

 Self-rated health prior to surgery

n/a

0.46⁺

**