Analysis of C-reactive protein (CRP) levels in pain patients – Can biomarker studies lead to better understanding of the pathophysiology of pain?

Abstract

In this issue of the Scandinavian Journal of Pain, Michele Sterling and co-authors present data showing that blood levels of the inflammatory biomarker serum C-reactive protein (CRP) seem to correlate to fMRI responses in regional brain areas, activated by noxious cold stimulation of the hand in patients with chronic whiplash associated disorders (WAD) [1]. The activated brain regions included the anterior insula, posterior parietal cortex, caudate and thalamus. The levels of TNF-alpha were not related to cerebral fMRI changes during pain stimuli, but a moderate positive correlation was found between blood levels of TNF and the psychological variable of pain catastrophizing. The study shows the interesting possibility to use analysis of biomarkers in blood as a way for deeper understanding of the biological aspect of pain, this elusive “bio-psycho-social” construct, combined with “imaging biomarkers” using fMRI. I think it is realistic to say that in the parts of the medical community, pain patients and pain treatment often are considered as “low status” work, and difficult to handle. One reason behind this view may be the fact that the golden standard of pain assessment is based upon the patient’s self-report only, and that objective, measurable findings usually are absent. Of course, we must trust the patient’s report, but I often wish that we had better tools to understand the nature of pain and its pathophysiology. “We need a CRP for pain”, a colleague pain clinician once said, “some lab test that would show that there is something measurable going on in the pain patient. This would improve the respect for the pain patients from the caregivers, and give the field of pain medicine a better status” (personal communication, Jens Draiby, 2014).