The aim of the SALT study is to analyze the relationship between dietary sodium intake and disease activity in patients with axial spondyloarthritis (radiographic or non-radiographic) or psoriatic arthritis.

Inclusion Criteria:

• patients with axial spondyloarthritis (radiographic or non-radiographic) or psoriatic arthritis
• women who have been menopausal for at least 24 months, surgically sterilized, or, for women of childbearing potentiale, use an effective method of contraception (oral contraceptives, contraceptive injections, intrauterine devices, double-barrier method, contraceptive patches)

Exclusion Criteria:

• patient treated by cyclosporine, diuretics, angiotensin-converting enzyme inhibitors or angiotensin II receptor antagonists.
• current treatment with an anti-IL-17A agent (secukinumab or ixekizumab or bimekizumab or brodalumab) or with an anti-IL23 agent (ustekinumab, guselkumab, risankizumab or tildrakizumab) or previous treatment less than 6 months old.
• patients on systemic corticosteroids with corticosteroid therapy > 10 mg prednisone equivalent
• pregnant woman