Inflammatory Markers May Diagnose Back Conditions

Biochemical profiles of blood may improve diagnosis of conditions contributing to low back pain (LBP), according to a study published online Jan. 7 in Arthritis Research & Therapy. LBP is associated with low-grade systemic inflammation and circulating cytokine levels may differentiate disc-related causes of pain.

LBP is a widespread and costly problem. It is the second most common cause of physician visits in the United States, affects the majority of people at some point during their lifetime, and is estimated to cost $50 billion to $100 billion in direct health care spending. Yet, timely and definitive diagnosis is a challenge as pain can have multiple potential causes that present similarly and respond unpredictably to treatment. Additionally, MRI imaging has been shown to have poor correlation to functional impairment or pain.

The researchers recruited participants (average age 50 years; 43 percent male) with LBP from a spine neurosurgery practice (n = 80) and a back pain management practice (n = 27), as well as a control cohort (n = 26). Serum samples were collected before treatment (either epidural steroid injection or surgery) and were assayed by multiplex electrochemiluminescence immunoassays for levels of multiple interleukins (IL), interferon- γ, tumor necrosis factor-α, and multiple matrix metalloproteinases (MMPs).

Controlling for age and gender effects, participants with LBP (combined epidural and surgery cohorts) had serum IL-6 levels that were significantly (41 percent) higher than control participants. Participants with LBP due to spinal stenosis or degenerative disc disease had higher IL-6 levels than those with intervertebral disc herniation and controls. In contrast, serum levels of MMP-1 were significantly (56 percent) lower in LBP participants than in controls. MMP-1 levels were lower specifically in patients with disc herniation versus control subjects. There were no significant differences in IL-6 or MMP-1 serum levels with respect to disease severity (classified by Pfirrmann grade).

"It is unknown if circulating cytokines are causative of degenerative changes and pain or whether elevated cytokine levels are a consequence of the degeneration and painful condition," write the authors led by Kathryn Weber, M.D., a clinical research fellow from the North Shore-LIJ Health System. "The possibility of using serum cytokine measures of IL-6 to predict response to treatment with progressively targeted therapies fits the emerging concept of personalized molecular medicine, where treatments are tailored to an individual's specific biology through increasingly sensitive detection of molecular abnormalities, and the use of these inflammatory mediators as biomarkers for LBP."

Takeaway: Diagnosis and treatment of LBP caused by disc disease may be improved through the use of biochemical profiling of circulating cytokines.