Background/Purpose: Rheumatoid arthritis (RA) is an autoimmune disease resulting from an interaction between genetic and environmental factors. Recently, sodium intake was suggested as a risk factor for autoimmune diseases by driving lymphocyte polarization toward a Th17 pathway. Our study aimed to assess sodium intake at RA diagnosis and in established RA and evaluate its impact on disease activity and severity.

Methods: The prospective cross-sectional study included 24 patients with RA at diagnosis (early RA) and 24 controls matched on age, gender and body mass index. Furthermore, 197 patients with established RA were included. Sodium intake was evaluated by 24-hr urinary sodium excretion, and the Food Frequency Questionnaire (FFQ) was used to evaluate potential diet confounding factors.

Results: Sodium intake was greater for patients with early RA (+650 mg/day of sodium, p=0.039) and established RA (p=0.046) than controls (figure 1) and was greater for patients with than without radiographic erosion at the time of diagnosis (p=0.028) (figure 2). It was lower for patients positive for rheumatoid factor and was not correlated with disease activity and severity for patients with established RA.

Conclusion: Patients with early and established RA show increased sodium consumption as compared to matched controls and that sodium consumption was associated with disease severity at diagnosis. Sodium may activate immune cells, which could worsen RA prognosis.