Sodium intake and multiple sclerosis activity and progression in BENEFIT

Abstract

Objective: To assess whether a high-salt diet, as measured by urinary sodium concentration, is associated with faster conversion from clinically isolated syndrome (CIS) to multiple sclerosis (MS) and MS activity and disability.

Methods: BENEFIT was a randomized clinical trial comparing early versus delayed interferon beta-1b treatment in 465 patients with a CIS. Each patient provided a median of 14 (IQR: 13 to 16) spot urine samples throughout the 5-year follow-up. We estimated 24-hour urine sodium excretion level at each time point using the Tanaka equations, and assessed whether sodium levels estimated from the cumulative average of the repeated measures were associated with clinical (conversion to MS, EDSS) and magnetic resonance imaging (MRI) outcomes.

Results: Average 24-hour urine sodium levels were not associated with conversion to clinically-definite MS over the 5-year follow-up (hazard ratio [HR]=0.91; 95% CI: 0.67-1.24 per 1g increase in estimated daily sodium intake); nor were they associated with clinical or MRI outcomes (new active lesions after 6 months HR: 1.05; 95% CI 0.97-1.13; relative change in T2 lesion volume: -0.11; 95% CI -0.25-0.04; change in EDSS: -0.01; 95% CI: -0.09-0.08; relapse rate HR: 0.78; 95% CI: 0.56-1.07). Results were similar in categorical analyses using quintiles.

Interpretation: Our results, based on multiple assessments of urine sodium excretion over 5 years and standardized clinical and MRI follow-up, suggest that salt intake does not influence MS disease course or activity. This article is protected by copyright. All rights reserved.

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