Biomarker clusters differentiate phenotypes of lumbar spine degeneration and low back pain: The Johnston County Osteoarthritis Project

Abstract

ObjectiveDescribe the association between biomarkers and lumbar spine degeneration (vertebral osteophytes [OST], facet joint osteoarthritis [FOA], and disc space narrowing [DSN]), for persons with and without low back pain (LBP) and determine whether clusters based on biomarkers differentiate lumbar spine structure with and without LBP. MethodsUsing data from the Johnston County Osteoarthritis Project (2006–2010), we measured serum N-cadherin, Keratin-19, Lumican, CXCL6, RANTES, HA, IL-6, BDNF, OPG, and NPY, and urinary CTX-II. Biomarkers were used to group participants using k-means cluster analysis. Logistic regression models were used to compare biomarker clusters. ResultsThe sample consisted of 731 participants with biospecimens and lumbar spine radiographic data. Three biomarker subgroups were identified: one characterized by structural degenerative changes; another characterized by structural degenerative changes and inflammation, with pain; and a referent cluster with lower levels of biomarkers, pain, and structural degenerative changes. Compared to the referent subgroup, the structural change subgroup was associated with DSN (OR ​= ​1.94, 95% CI 1.30–2.90) and FOA (OR ​= ​1.72, 95% CI 1.12–2.62), and the subgroup with structural degenerative change, inflammation, and pain was associated with OST with LBP (OR ​= ​1.60, 95% CI 1.04–2.46), FOA with LBP (OR ​= ​1.59, 95% CI 1.04–2.45), and LBP (OR ​= ​1.63, 95% CI 1.11–2.41). The subgroup with structural degenerative changes was more likely to have OST (OR ​= ​1.82, 95% CI 1.06–3.13) and less likely to have FOA with LBP (OR ​= ​0.62, 95% CI 0.40–0.96) compared to the group with inflammation and pain. ConclusionClustering by biomarkers may assist in differentiating patients for specific clinical interventions aimed at decreasing LBP.