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

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

  Pearsons correlation coefficient
Prior to surgery P-value 12 months P-value
Demographic characteristics
 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  
Clinical characteristics
 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  
Pain characteristics
 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+ **
Perioperative characteristics:
 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  
Preoperative symptoms
 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+ **
Psychological characteristics***
 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+ **
Health characteristics
 Self-rated health prior to surgery n/a   0.46+ **
  1. *Correlation is significant at the 0.05 level (2 tailed)
  2. ** Correlation is significant at the 0.01 level (2 tailed)
  3. *** Single item scores from the Brief Illness Perception Questionnaire
  4. n/a = not applicable
  5. +Selected for inclusion in linear regressions