Associations between serum biomarkers and pain and pain-related function in older adults with low back pain: a pilot study.

Objectives: To examine the relationship between serum biomarkers and self-reported pain intensity and pain-related function, in addition to the contribution of magnetic resonance imaging (MRI) findings of lumbar spine degenerative changes, in older adults with chronic low back pain.

Design: Single-center cross-sectional cohort study.

Setting: Academic medical center.

Participants: Individuals aged 60 and older with axial low back pain without radiculopathy or previously diagnosed osteoarthritis of the knee or hip or pain outside the low back that is more severe than the back pain (n = 43).

Measurements: To examine pain-related impairment, pain was measured on a pain thermometer and the McGill Pain Questionnaire Short Form was administered. To examine pain-related function or activity limitation, the Roland Morris Disability Questionnaire, Short Physical Performance Battery (SPPB), and repetitive trunk rotation were used. Single plasma samples were obtained before and after physical performance tests and analyzed for inflammatory markers (E-selectin and regulated on activation, normal T cell expressed and secreted (RANTES)), inhibitors of catabolic enzymes (tissue inhibitor of metalloproteinases-1 (TIMP-1)), markers of matrix turnover (C- telopeptide of type II collagen (CTX-II) and aggrecan chondroitin sulfate 846 (CS846)), and stress biomarkers (neuropeptide Y (NPY)). Conventional nongadolinium lumbar MRI was performed and analyzed quantitatively and clinically.

Results: Composite MRI measurements did not show significant correlation with pain or pain-related function. Basal levels and changes in serum biomarkers in response to activity, particularly NPY and RANTES, demonstrated associations with pain and pain-related function in addition to the explanatory power of MRI-based results.

Conclusion: Serum biomarkers may be a metric for assessment of active disease in older adults, in whom imaging changes are ubiquitous. In addition, changing levels of biomarkers in response to activity suggests that they may be useful as metrics to measure treatment responses in future studies and may reflect potential targets for use in designing personalized treatment for older adults with low back pain.