Expression of Inflammation-Related Proteins and Use of Analgesics Before and after Interdisciplinary Pain Rehabilitation - a Secondary Analysis.

OBJECTIVES:Current pharmacological treatments of chronic pain are largely ineffective, one reason being that the pathophysiological mechanisms driving chronic pain are not yet elucidated. Emerging evidence, including human biomarker studies, suggests that neuroimmune activation and chronic low-grade inflammation are present. However, some patients with chronic pain regularly use analgesics, including nonsteroidal anti-inflammatory drugs (NSAIDs), and it is not clear how such medication might impact the low-grade systemic inflammation pattern of the individual patient. METHODS:This secondary analysis of partially published data was undertaken to explore the relationship between the concentrations of 71 pro- and anti-inflammatory plasma proteins and the use of various analgesic medications (including NSAIDs) in patients participating in interdisciplinary pain multimodal rehabilitation programs for chronic pain. RESULTS:At baseline (n=27), 63 % of patients used paracetamol, 33 % used NSAIDs, 19 % used opioids, 19 % used antidepressants (duloxetine, amitriptyline or mirtazapine), 11 % used chlorzoxazone, 7 % used corticosteroids, and 0 % used gabapentinoids. Using hierarchical cluster analysis, we identified two subgroups of patients - a "high inflammation" and a "low inflammation" subgroup. The main finding was that the distribution of analgesics, including NSAIDs, between the two groups did not differ. However, the low number of subjects must be acknowledged, implying low power and the risk of false negative results. CONCLUSIONS:Larger studies, e.g., focusing on NSAID users before and after treatment discontinuation, are needed to further ascertain the impact of specific medication on the systemic inflammation pattern of chronic pain patients.