Page 160 - THE PERCEPT STUDY Illness Perceptions in Physiotherapy Edwin de Raaij

Chapter 8
2. The additional association of Illness Perceptions with pain or limitations in physical func- tioning in chapter 4.
Research question:
What is the additional association of Illness Perceptions with pain intensity or limitations in physical functioning in addition to the independent factors pain sites, pain duration, and the psychological factors somatization, distress, anxiety, and depression in patients with muscu- loskeletal pain, adjusted for gender and age? A cross-sectional cohort study.
Summary of main findings
On most IP dimensions there were only small differences in scores between patients with acute, subacute or persistent pain. In addition to some well-known prognostic factors (num- ber of pain sites, pain duration, and the psychological factors somatization, distress, anxiety, and depression), higher scores on the IP dimensions Consequences, Identity and Coherence are associated with higher pain intensity. For physical functioning, the IP dimensions Conse- quences, Treatment Control, Identity and Concern are associated with more limitations.
For cross-sectional associations our findings are in line with our systematic review: a higher IP score indicates higher pain scores and more limitations in physical functioning. However, due to the cross-sectional design these results do not support the prognostic value of IPs.
Discussion
With exception of the IP dimension Timeline, we found no clinically relevant mean differences for the other 7 IP dimensions in acute, subacute or persistent phase of MSP. These findings are in line with qualitative research that reported comparable beliefs of vulnerability and poor prognosis among people with acute or persistent low back pain13. Therefore, it may by equally important to integrate IPs in physiotherapy management of chronic and acute MSP.
Methodological considerations
The associations that were reported in this study are small to moderate. IPs not being strong- ly associated with pain and physical functioning can be understood when taking into account that pain and physical functioning are associated with a large variety of biopsychosocial fac- tors. Meaning that strong associations are not to be expected for any one individual factor. Nevertheless, the outcomes of this study for the IPs association with pain still showed that the IP dimensions added a 13.3% explained variance (total 22.9%) and for physical function- ing 26.5% additional explained variance (total 32.2%), which means that IPs were seen as a contributing factor in the explained variance.
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