Table 2.
Effect of inflammation before treatment on the treatment-induced changes in pain-related variables
| Dependent variable | Independent variable | R 2 | β | p |
|---|---|---|---|---|
| Pain intensity | Composite score IL-6/TNF- α | .250 | .405 | .011 |
| Composite score IL-6/TNF- α/IL-8 | .190 | .308 | .053 | |
| Pain disability (PDI) | Composite score IL-6/TNF- α | .266 | .134 | .377 |
| Composite score IL-6/TNF- α/IL-8 | .268 | .138 | .353 | |
| Psychological inflexibility (PIPS) | Composite score IL-6/TNF- α | .367 | .395 | .007 |
| Composite score IL-6/TNF- α/IL-8 | .294 | .275 | .064 | |
| Physical health-related QOL (PCS) | Composite score IL-6/TNF- α | .077 | −.054 | .754 |
| Composite score IL-6/TNF- α/IL-8 | .071 | −.010 | .952 | |
| Mental health-related QOL (MCS) | Composite score IL-6/TNF- α | .311 | −.335 | .029 |
| Composite score IL-6/TNF- α/IL-8 | .310 | −.326 | .030 |
Separate linear regression analyses. Dependent variables are the relative changes from pre- to post-treatment [= (post-treatment − pre-treatment)/pre-treatment)]. Independent variables are pre-treatment composite scores, extracted using principal component analyses, using logarithm-transformed IL-6 and TNF-α pre-treatment concentrations (composite score IL-6/TNF-α) or the three cytokines, logarithm-transformed IL-6, TNF-α and IL-8 concentrations (composite score IL-6/TNF-α/IL-8). Regression analyses were adjusted for age, gender, the change in number of used medicines and the relative change in anxiety and depressive symptoms (HADS). Bold font represents significant values (p < .05)
TNF-α tumor necrosis factor-α, IL-6 interleukin-6, IL-8 interleukin-8, PDI pain disability, PIPS psychological inflexibility, QOL quality of life, PCS physical health-related quality of life, MCS mental health-related quality of life, HADS Hospital Anxiety and Depression Scale