Table 1.
Potential predictors to self-rated health prior to surgery and 12 months following total knee arthroplasty – Pearsons bivariate correlation coefficient
| 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+ | ** | |
*Correlation is significant at the 0.05 level (2 tailed)
** Correlation is significant at the 0.01 level (2 tailed)
*** Single item scores from the Brief Illness Perception Questionnaire
n/a = not applicable
+Selected for inclusion in linear regressions