Linking serum neurofilament light chain to arthritis: Insights from a national population-based study.

Arthritis affects millions globally and imposes significant burdens on individual well-being and public health systems. Serum neurofilament light chain (sNFL) has been implicated in various neuroinflammatory and systemic conditions. However, its potential association with arthritis has not been explored in population-based settings. We analyzed data from the 2013 to 2014 National Health and Nutrition Examination Survey, including 2068 adults aged 20 years or older with available sNFL measurements and arthritis status based on self-reported physician diagnosis. Serum sNFL concentrations were quantified using a high-sensitivity chemiluminescence-based immunoassay. Multivariable logistic regression was used to estimate the association between sNFL levels and the odds of arthritis, adjusting for sociodemographic, lifestyle, and clinical factors. Subgroup and interaction analyses were performed to examine effect modification. Elevated serum sNFL levels were significantly associated with higher odds of having arthritis. After full covariate adjustment, each 1-unit increase in log-transformed sNFL was associated with an 85% increase in arthritis odds (odd ratio = 1.85; 95% confidence interval: 1.79-2.39). Participants in the highest sNFL quartile had 3.67 times higher odds of arthritis compared to those in the lowest quartile (P for trend = .003). Subgroup analyses indicated stronger associations in individuals with higher education and those without diabetes or hypertension (P for interaction < .05). This nationally representative analysis demonstrates a significant association between circulating sNFL levels and the presence of arthritis, suggesting that sNFL may reflect broader systemic or inflammatory processes linked to joint pathology. These findings support further investigation of sNFL as a potential biomarker for arthritis risk stratification.